BlackTreeCVE Intelligence
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Full vulnerability report · 2019
CVE-2019-9517High confidence

Some HTTP/2 implementations are vulnerable to unconstrained interal data buffering, potentially leading to a denial of service

Unknown · Unknown

7.5HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Critical, raised one band.upgradedsince 23 Oct 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 27.89% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Unknown Unknown and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Distribution package intelligence

Release-specific package status

Alpine, Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

10 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Alpine v3.23v3.23 · mainapache2Vendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.2.4.41-r0Alpine Security Database ↗Source updated 23 Oct 2026
Alpine v3.23v3.23 · mainnodejsVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.10.16.3-r0Alpine Security Database ↗Source updated 23 Oct 2026
Alpine v3.22v3.22 · mainapache2Vendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.2.4.41-r0Alpine Security Database ↗Source updated 23 Oct 2026
Alpine v3.22v3.22 · mainnodejsVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.10.16.3-r0Alpine Security Database ↗Source updated 23 Oct 2026
Alpine v3.21v3.21 · mainapache2Vendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.2.4.41-r0Alpine Security Database ↗Source updated 23 Oct 2026
Alpine v3.21v3.21 · mainnodejsVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.10.16.3-r0Alpine Security Database ↗Source updated 23 Oct 2026
Debian trixietrixie · sourceapache2Vendor fix publishedDebian records a fixed source-package version for this release.2.4.41-1Debian Security Tracker ↗Source updated 23 Oct 2026
Debian bookwormbookworm · sourceapache2Vendor fix publishedDebian records a fixed source-package version for this release.2.4.41-1Debian Security Tracker ↗Source updated 23 Oct 2026
Debian forkyforky · sourceapache2Vendor fix publishedDebian records a fixed source-package version for this release.2.4.41-1Debian Security Tracker ↗Source updated 23 Oct 2026
Debian sidsid · sourceapache2Vendor fix publishedDebian records a fixed source-package version for this release.2.4.41-1Debian Security Tracker ↗Source updated 23 Oct 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

2 current
CVE-2019-9517 · CSAF 2.0 · revision 40 · interimSUSE Product Security TeamCVE-2019-9517
284 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • apache2 as component of HPE Helion OpenStack 8
  • apache2-doc as component of HPE Helion OpenStack 8
  • apache2-example-pages as component of HPE Helion OpenStack 8
  • apache2-prefork as component of HPE Helion OpenStack 8
  • apache2-utils as component of HPE Helion OpenStack 8
  • apache2-worker as component of HPE Helion OpenStack 8
  • apache2 as component of SUSE CaaS Platform 4.0
  • apache2-devel as component of SUSE CaaS Platform 4.0
  • apache2-doc as component of SUSE CaaS Platform 4.0
  • apache2-prefork as component of SUSE CaaS Platform 4.0
  • apache2-utils as component of SUSE CaaS Platform 4.0
  • apache2-worker as component of SUSE CaaS Platform 4.0
Summary
Some HTTP/2 implementations are vulnerable to unconstrained interal data buffering, potentially leading to a denial of service. The attacker opens the HTTP/2 window so the peer can send without constraint; however, they leave the TCP window closed so the peer cannot actually write (many of) the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the servers queue the responses, this can consume excess memory, CPU, or both.
Remediation
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
CVE-2019-9517 · CSAF 2.0 · revision 3 · finalRed Hat Product SecurityHTTP/2: request for large response leads to denial of service
5 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • jetty as a component of Red Hat AMQ Broker 7
  • undertow-core as a component of Red Hat JBoss Enterprise Application Platform 7
  • httpd.src as a component of Red Hat JBoss Enterprise Web Server 3
  • undertow as a component of Red Hat JBoss Fuse 6
  • rhoar-nodejs as a component of Red Hat OpenShift Application Runtimes
Summary
A vulnerability was found in HTTP/2. An attacker can open a HTTP/2 window so the peer can send without constraint. The TCP window remains closed so the peer cannot write the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the server's queue is setup, the responses can consume excess memory, CPU, or both, potentially leading to a denial of service. The highest threat from this vulnerability is to system availability.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 For the update to take effect, all services linked to the OpenSSL library must be restarted, or the system rebooted. After installing the updated packages, the httpd daemon will be restarted automatically.
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2019-18889

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

Some HTTP/2 implementations are vulnerable to unconstrained interal data buffering, potentially leading to a denial of service. The attacker opens the HTTP/2 window so the peer can send without constraint; however, they leave the TCP window closed so the peer cannot actually write (many of) the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the servers queue the responses, this can consume excess memory, CPU, or both.

What

Some HTTP/2 implementations are vulnerable to unconstrained interal data buffering, potentially leading to a denial of service. The attacker opens the HTTP/2 window so the peer can send without constraint; however, they leave the TCP window closed so the peer cannot actually write (many of) the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the servers queue the responses, this can consume excess memory, CPU, or both.

Why

The product does not properly control the allocation and maintenance of a limited resource.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

What

Some HTTP/2 implementations are vulnerable to unconstrained interal data buffering, potentially leading to a denial of service. The attacker opens the HTTP/2 window so the peer can send without constraint; however, they leave the TCP window closed so the peer cannot actually write (many of) the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the servers queue the responses, this can consume excess memory, CPU, or both.

Why

The product does not properly control the allocation and maintenance of a limited resource.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Uncontrolled Resource Consumption → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-400 ↗

CWE-400: Uncontrolled Resource Consumption. The product does not properly control the allocation and maintenance of a limited resource.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedDenial of serviceCWE-400
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2024-1591Juniper JUNOS: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Juniper JUNOS ausnutzen, um einen Denial of Service zu verursachen, Informationen offenzulegen, Privilegien zu erweitern und Sicherheitsmechanismen inklusive zu umgehen.

Official advisory ↗
Canadian Centre for Cyber Security · English · AV19-179Apache security advisory

On 26 August 2019 Debian released a security advisory to address multiple Apache vulnerabilities. A local actor could exploit these vulnerabilities to take control of an affected system. Please note that other versions of Linux may also be affected. The vulnerabilities are identified by the following CVE’s:

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0109Multiples vulnérabilités dans les produits IBM

29 janvier 2026 https://www.ibm.com/support/pages/node/7257633 Bulletin de sécurité IBM 7257678 du 29 janvier 2026 https://www.ibm.com/support/pages/node/7257678 Bulletin de sécurité IBM 7258331 du 29 janvier 2026 https://www.ibm.com/support/pages/node/7258331 Référence CVE CVE-2016-2193 https://www.cve.org/CVERecord?id=CVE-2016-2193 Référence CVE CVE-2019-9512 https://www.cve.org/CVERecord?id=CVE-2019-9512 Référence CVE CVE-2019-9513 https://www.cve.org/CVERecord?id=CVE-2019-9513 Référence CVE CVE-2019-9514 https://www.cve.org/CVERecord?id=CVE-2019-9514 Référence CVE CVE-2019-9515 https://www.cve.org/CVERecord?id=CVE-2019-9515 Référence CVE CVE-2019-9517 https://www.cve.org/CVERecord?id=CVE-2019-9517 Référence CVE CVE-2019-9518 https://www.cve.org/CVERecord?id=CVE-2019-9518 Référence CVE CVE-2021-23413 https://www.cve.org/CVERecord?id=CVE-2021-23413 Référence CVE CVE-2022-22968 https://www.cve.org/CVERecord?id=CVE-2022-22968 Référence CVE CVE-2022-25858 https://www.cve.org/CVERecord?id=CVE-2022-25858 Référence CVE CVE-2022-25881 https://www.cve.org/CVERecord?id=CVE-2022-25881 Référence CVE CVE-2022-25883 https://www.cve.org/CVERecord?id=CVE-2022-25883 Référence CVE CVE-2022-2596 https://www.cve.org/CVERecord?id=CVE-2022-2596 Référence CVE CVE-2022-33987 https://www.cve.org/CVERecord?id=CVE-2

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0575Multiples vulnérabilités dans les produits Juniper Networks

d?id=CVE-2019-11727 Référence CVE CVE-2019-11756 https://www.cve.org/CVERecord?id=CVE-2019-11756 Référence CVE CVE-2019-16775 https://www.cve.org/CVERecord?id=CVE-2019-16775 Référence CVE CVE-2019-16776 https://www.cve.org/CVERecord?id=CVE-2019-16776 Référence CVE CVE-2019-16777 https://www.cve.org/CVERecord?id=CVE-2019-16777 Référence CVE CVE-2019-17006 https://www.cve.org/CVERecord?id=CVE-2019-17006 Référence CVE CVE-2019-17023 https://www.cve.org/CVERecord?id=CVE-2019-17023 Référence CVE CVE-2019-17567 https://www.cve.org/CVERecord?id=CVE-2019-17567 Référence CVE CVE-2019-20149 https://www.cve.org/CVERecord?id=CVE-2019-20149 Référence CVE CVE-2019-9517 https://www.cve.org/CVERecord?id=CVE-2019-9517 Référence CVE CVE-2020-11668 https://www.cve.org/CVERecord?id=CVE-2020-11668 Référence CVE CVE-2020-11984 https://www.cve.org/CVERecord?id=CVE-2020-11984 Référence CVE CVE-2020-11993 https://www.cve.org/CVERecord?id=CVE-2020-11993 Référence CVE CVE-2020-12362 https://www.cve.org/CVERecord?id=CVE-2020-12362 Référence CVE CVE-2020-12400 https://www.cve.org/CVERecord?id=CVE-2020-12400 Référence CVE CVE-2020-12401 https://www.cve.org/CVERecord?id=CVE-2020-12401 Référence CVE CVE-2020-12402 https://www.cve.org/CVERecord?id=CVE-2020-12402 Référence CVE CVE-2020-12403 https://www.cve.org/CVERecord?id=C

Official advisory ↗
CERT-FR · French · CERTFR-2020-AVI-175Multiples vulnérabilités dans IBM WebSphere Liberty

De multiples vulnérabilités ont été découvertes dans IBM WebSphere Liberty. Elles permettent à un attaquant de provoquer un déni de service à distance.

Official advisory ↗
CERT-FR · French · CERTFR-2020-AVI-111Multiples vulnérabilités dans IBM WebSphere Liberty

De multiples vulnérabilités ont été découvertes dans IBM WebSphere Liberty. Elles permettent à un attaquant de provoquer un déni de service à distance.

Official advisory ↗
CERT-FR · French · CERTFR-2020-AVI-064Multiples vulnérabilités dans IBM Control Center

De multiples vulnérabilités ont été découvertes dans IBM Control Center. Elles permettent à un attaquant de provoquer un déni de service à distance.

Official advisory ↗
CERT-FR · French · CERTFR-2019-AVI-402Multiples vulnérabilités dans Apache Httpd

De multiples vulnérabilités ont été découvertes dans Apache Httpd. Elles permettent à un attaquant de provoquer un problème de sécurité non spécifié par l'éditeur et un déni de service à distance.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2019-008014Apple SwiftNIO および Apache Traffic Server で使用される HTTP/2 における制限またはスロットリング無しのリソースの割り当てに関する脆弱性

Apple SwiftNIO および Apache Traffic Server で使用される HTTP/2 には、制限またはスロットリング無しのリソースの割り当てに関する脆弱性が存在します。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 For the update to take effect, all services linked to the OpenSSL library must be restarted, or the system rebooted. After installing the updated packages, the httpd daemon will be restarted automatically.
Action
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 13 Aug 2019 · Last source change 4 Aug 2024, 21:54 UTC · CWE-400 · Uncontrolled Resource Consumption

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-01
European sourceENISA EUVD · EUVD-2019-18889
Product sourceVendor CSAF · SUSE Product Security Team
Remediation sourceVendor CSAF · SUSE Product Security Team
CWE sourceCNA
NVD statusNVD modified after enrichment

Missing structured fields: affected product. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed from advisory no longer present in the provider's current catalogue to remediation: access.redhat.com/CVE-2019-9517.
    Before
    advisory no longer present in the provider's current catalogue
    After
    remediation: access.redhat.com/CVE-2019-9517
    Red Hat Product Security ↗
  2. Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2019-9517 to advisory no longer present in the provider's current catalogue.
    Before
    remediation: access.redhat.com/CVE-2019-9517
    After
    advisory no longer present in the provider's current catalogue
    Red Hat Product Security ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    n/a · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    n/a · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 For the update to take effect, all services linked to the OpenSSL library must be restarted, or the system rebooted. After installing the updated packages, the httpd daemon will be restarted automatically.
    Red Hat Product Security ↗
  4. ENISA EUVD mappingEUVD-2019-18889 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2019-18889"}
    ENISA EUVD ↗
  5. Vendor guidanceAuthoritative vendor guidance changed: added patch: oracle.com/cpuoct2019-5072832.html; added remediation: oracle.com/cpuoct2019-5072832.html; removed vendor advisory: access.redhat.com/RHSA-2019:2893; removed vendor advisory: access.redhat.com/RHSA-2019:2925; 18 further removals.
    Before
    vendor advisory: access.redhat.com/RHSA-2019:2893 · vendor advisory: access.redhat.com/RHSA-2019:2925 · vendor advisory: access.redhat.com/RHSA-2019:2939 · 17 more references
    After
    patch: oracle.com/cpuoct2019-5072832.html · remediation: oracle.com/cpuoct2019-5072832.html
    oracle.com ↗
  6. Affected versionsThe structured affected or fixed version information changed.
    Before
    n/a · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    n/a · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
  7. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    oracle.com ↗
  8. CVSS scoreCVSS version changed from 3.0 to 3.1; the displayed base score remains 7.5.
    Before
    7.5 (CVSS 3.0 · CNA · CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
    After
    7.5 (CVSS 3.1 · NIST NVD · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
    NIST NVD ↗
  9. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
Fixed release recorded from official guidance
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2019-18889↗Vendor CSAF · SUSE Product Security Team↗Red Hat Product Security security advisory↗Patch or update reference↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2019-9517 · cve.blacktree.nl