BlackTreeCVE Intelligence
← Back to the CVE catalogue
Full vulnerability report · 2021
CVE-2021-33194High confidence

golang.org/x/net before v0.0.0-20210520170846-37e1c6afe023 allows attackers to cause a denial of service (infinite loop) via crafted ParseFragment input

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:High, unchanged from published severity.unchanged

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 7.49% 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 30 daysRemediation target: Within 180 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

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

4 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
Debian trixietrixie · sourcegolang-golang-x-netVendor fix publishedDebian records a fixed source-package version for this release.1:0.0+git20210119.5f4716e+dfsg-4Debian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourcegolang-golang-x-netVendor fix publishedDebian records a fixed source-package version for this release.1:0.0+git20210119.5f4716e+dfsg-4Debian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourcegolang-golang-x-netVendor fix publishedDebian records a fixed source-package version for this release.1:0.0+git20210119.5f4716e+dfsg-4Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcegolang-golang-x-netVendor fix publishedDebian records a fixed source-package version for this release.1:0.0+git20210119.5f4716e+dfsg-4Debian Security Tracker ↗Source updated 6 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.

1 current
CVE-2021-33194 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitygolang: x/net/html: infinite loop in ParseFragment
75 known affected

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

  • openshift-logging/cluster-logging-rhel8-operator as a component of Logging Subsystem for Red Hat OpenShift
  • servicemesh as a component of OpenShift Service Mesh 2.0
  • servicemesh-istioctl as a component of OpenShift Service Mesh 2.0
  • servicemesh-mixc as a component of OpenShift Service Mesh 2.0
  • servicemesh-mixs as a component of OpenShift Service Mesh 2.0
  • servicemesh-pilot-agent as a component of OpenShift Service Mesh 2.0
  • servicemesh-pilot-discovery as a component of OpenShift Service Mesh 2.0
  • servicemesh.src as a component of OpenShift Service Mesh 2.0
  • golang-bin as a component of Red Hat Ceph Storage 2
  • golang-src as a component of Red Hat Ceph Storage 2
  • golang.src as a component of Red Hat Ceph Storage 2
  • grafana as a component of Red Hat Ceph Storage 2
Summary
A flaw was found in golang. An attacker can craft an input to ParseFragment within parse.go that would cause it to enter an infinite loop and never return. The greatest threat to the system is of availability.
Remediation
For OpenShift Container Platform 4.9 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this errata update: https://docs.openshift.com/container-platform/4.9/release_notes/ocp-4-9-release-notes.html For Red Hat OpenShift Logging 5.3, see the following instructions to apply this update: https://docs.openshift.com/container-platform/4.7/logging/cluster-logging-upgrading.html
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-2022-3094

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

golang.org/x/net before v0.0.0-20210520170846-37e1c6afe023 allows attackers to cause a denial of service (infinite loop) via crafted ParseFragment input.

What

golang.org/x/net before v0.0.0-20210520170846-37e1c6afe023 allows attackers to cause a denial of service (infinite loop) via crafted ParseFragment input.

Why

A malformed condition prevents a loop from making progress or terminating, allowing resource exhaustion.

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

golang.org/x/net before v0.0.0-20210520170846-37e1c6afe023 allows attackers to cause a denial of service (infinite loop) via crafted ParseFragment input.

Why

A malformed condition prevents a loop from making progress or terminating, allowing resource exhaustion.

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 → Loop with Unreachable Exit Condition ('Infinite Loop') → 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-835 ↗

CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop'). The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

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-835
A

Official authority intelligence

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

BSI · German · WID-SEC-2024-0794Dell ECS: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Dell ECS ausnutzen, um seine Privilegien zu erweitern, beliebigen Programmcode mit Administratorrechten auszuführen, Informationen offenzulegen, Dateien zu manipulieren, einen Cross-Site-Scripting-Angriff durchzuführen, Sicherheitsvorkehrungen zu umgehen oder einen Denial of Service Zustand herbeizuführen.

Official advisory ↗
BSI · German · WID-SEC-2023-2229Splunk Splunk Enterprise: Mehrere Schwachstellen

Ein entfernter, authentifizierter Angreifer kann mehrere Schwachstellen in Splunk Splunk Enterprise ausnutzen, um beliebigen Code auszuführen, einen 'Denial of Service'-Zustand zu verursachen, seine Privilegien zu erweitern und weitere, nicht spezifizierte Auswirkungen zu verursachen.

Official advisory ↗
BSI · German · WID-SEC-2022-0510IBM DB2: Mehrere Schwachstellen

Ein entfernter, anonymer, authentisierter oder lokaler Angreifer kann mehrere Schwachstellen in IBM DB2 ausnutzen, um Dateien zu manipulieren, Sicherheitsmaßnahmen zu umgehen, vertrauliche Informationen offenzulegen, einen Denial-of-Service-Zustand auszulösen, willkürlichen Code mit erhöhten Rechten auszuführen, Informationen falsch darzustellen und beliebigen Code auszuführen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20210602Security Bulletin 02 Jun 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 02 Jun 2021, published on 2 June 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0305Multiples vulnérabilités dans les produits IBM

ord?id=CVE-2019-16163 Référence CVE CVE-2019-19012 https://www.cve.org/CVERecord?id=CVE-2019-19012 Référence CVE CVE-2019-19203 https://www.cve.org/CVERecord?id=CVE-2019-19203 Référence CVE CVE-2019-19204 https://www.cve.org/CVERecord?id=CVE-2019-19204 Référence CVE CVE-2020-28241 https://www.cve.org/CVERecord?id=CVE-2020-28241 Référence CVE CVE-2020-7656 https://www.cve.org/CVERecord?id=CVE-2020-7656 Référence CVE CVE-2021-22696 https://www.cve.org/CVERecord?id=CVE-2021-22696 Référence CVE CVE-2021-30468 https://www.cve.org/CVERecord?id=CVE-2021-30468 Référence CVE CVE-2021-31525 https://www.cve.org/CVERecord?id=CVE-2021-31525 Référence CVE CVE-2021-33194 https://www.cve.org/CVERecord?id=CVE-2021-33194 Référence CVE CVE-2021-35937 https://www.cve.org/CVERecord?id=CVE-2021-35937 Référence CVE CVE-2021-35938 https://www.cve.org/CVERecord?id=CVE-2021-35938 Référence CVE CVE-2021-35939 https://www.cve.org/CVERecord?id=CVE-2021-35939 Référence CVE CVE-2021-41043 https://www.cve.org/CVERecord?id=CVE-2021-41043 Référence CVE CVE-2022-2127 https://www.cve.org/CVERecord?id=CVE-2022-2127 Référence CVE CVE-2022-23437 https://www.cve.org/CVERecord?id=CVE-2022-23437 Référence CVE CVE-2022-27664 https://www.cve.org/CVERecord?id=CVE-2022-27664 Référence CVE CVE-2022-3094 https://www.cve.org/CVERecord?id=CVE

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0145Multiples vulnérabilités dans les produits IBM

ord?id=CVE-2021-22923 Référence CVE CVE-2021-22925 https://www.cve.org/CVERecord?id=CVE-2021-22925 Référence CVE CVE-2021-22926 https://www.cve.org/CVERecord?id=CVE-2021-22926 Référence CVE CVE-2021-22946 https://www.cve.org/CVERecord?id=CVE-2021-22946 Référence CVE CVE-2021-22947 https://www.cve.org/CVERecord?id=CVE-2021-22947 Référence CVE CVE-2021-27918 https://www.cve.org/CVERecord?id=CVE-2021-27918 Référence CVE CVE-2021-29923 https://www.cve.org/CVERecord?id=CVE-2021-29923 Référence CVE CVE-2021-3114 https://www.cve.org/CVERecord?id=CVE-2021-3114 Référence CVE CVE-2021-31525 https://www.cve.org/CVERecord?id=CVE-2021-31525 Référence CVE CVE-2021-33194 https://www.cve.org/CVERecord?id=CVE-2021-33194 Référence CVE CVE-2021-33195 https://www.cve.org/CVERecord?id=CVE-2021-33195 Référence CVE CVE-2021-33196 https://www.cve.org/CVERecord?id=CVE-2021-33196 Référence CVE CVE-2021-33197 https://www.cve.org/CVERecord?id=CVE-2021-33197 Référence CVE CVE-2021-33198 https://www.cve.org/CVERecord?id=CVE-2021-33198 Référence CVE CVE-2021-34558 https://www.cve.org/CVERecord?id=CVE-2021-34558 Référence CVE CVE-2021-36221 https://www.cve.org/CVERecord?id=CVE-2021-36221 Référence CVE CVE-2021-3711 https://www.cve.org/CVERecord?id=CVE-2021-3711 Référence CVE CVE-2021-3712 https://www.cve.org/CVERecord?id=CVE

Official advisory ↗
CERT-FR · French · CERTFR-2023-AVI-0701Multiples vulnérabilités dans Splunk

d?id=CVE-2021-23382 Référence CVE CVE-2021-27918 https://www.cve.org/CVERecord?id=CVE-2021-27918 Référence CVE CVE-2021-27919 https://www.cve.org/CVERecord?id=CVE-2021-27919 Référence CVE CVE-2021-29060 https://www.cve.org/CVERecord?id=CVE-2021-29060 Référence CVE CVE-2021-29425 https://www.cve.org/CVERecord?id=CVE-2021-29425 Référence CVE CVE-2021-29923 https://www.cve.org/CVERecord?id=CVE-2021-29923 Référence CVE CVE-2021-30560 https://www.cve.org/CVERecord?id=CVE-2021-30560 Référence CVE CVE-2021-31525 https://www.cve.org/CVERecord?id=CVE-2021-31525 Référence CVE CVE-2021-31566 https://www.cve.org/CVERecord?id=CVE-2021-31566 Référence CVE CVE-2021-33194 https://www.cve.org/CVERecord?id=CVE-2021-33194 Référence CVE CVE-2021-33195 https://www.cve.org/CVERecord?id=CVE-2021-33195 Référence CVE CVE-2021-33196 https://www.cve.org/CVERecord?id=CVE-2021-33196 Référence CVE CVE-2021-33197 https://www.cve.org/CVERecord?id=CVE-2021-33197 Référence CVE CVE-2021-33198 https://www.cve.org/CVERecord?id=CVE-2021-33198 Référence CVE CVE-2021-34558 https://www.cve.org/CVERecord?id=CVE-2021-34558 Référence CVE CVE-2021-3520 https://www.cve.org/CVERecord?id=CVE-2021-3520 Référence CVE CVE-2021-3572 https://www.cve.org/CVERecord?id=CVE-2021-3572 Référence CVE CVE-2021-36221 https://www.cve.org/CVERecord?id=CVE-

Official advisory ↗
CERT-FR · French · CERTFR-2022-AVI-591Multiples vulnérabilités dans les produits IBM

ord?id=CVE-2021-25741 Référence CVE CVE-2021-27918 https://www.cve.org/CVERecord?id=CVE-2021-27918 Référence CVE CVE-2021-28950 https://www.cve.org/CVERecord?id=CVE-2021-28950 Référence CVE CVE-2021-28971 https://www.cve.org/CVERecord?id=CVE-2021-28971 Référence CVE CVE-2021-29650 https://www.cve.org/CVERecord?id=CVE-2021-29650 Référence CVE CVE-2021-30465 https://www.cve.org/CVERecord?id=CVE-2021-30465 Référence CVE CVE-2021-3121 https://www.cve.org/CVERecord?id=CVE-2021-3121 Référence CVE CVE-2021-31525 https://www.cve.org/CVERecord?id=CVE-2021-31525 Référence CVE CVE-2021-31916 https://www.cve.org/CVERecord?id=CVE-2021-31916 Référence CVE CVE-2021-33194 https://www.cve.org/CVERecord?id=CVE-2021-33194 Référence CVE CVE-2021-3538 https://www.cve.org/CVERecord?id=CVE-2021-3538 Référence CVE CVE-2021-3573 https://www.cve.org/CVERecord?id=CVE-2021-3573 Référence CVE CVE-2021-3635 https://www.cve.org/CVERecord?id=CVE-2021-3635 Référence CVE CVE-2021-3669 https://www.cve.org/CVERecord?id=CVE-2021-3669 Référence CVE CVE-2021-3764 https://www.cve.org/CVERecord?id=CVE-2021-3764 Référence CVE CVE-2021-38201 https://www.cve.org/CVERecord?id=CVE-2021-38201 Référence CVE CVE-2021-4002 https://www.cve.org/CVERecord?id=CVE-2021-4002 Référence CVE CVE-2021-4028 https://www.cve.org/CVERecord?id=CVE-2021-4028

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-007537golang.org/x/net における無限ループに関する脆弱性

golang.org/x/net には、無限ループ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
Action
For OpenShift Container Platform 4.9 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this errata update: https://docs.openshift.com/container-platform/4.9/release_notes/ocp-4-9-release-notes.html For Red Hat OpenShift Logging 5.3, see the following instructions to apply this update: https://docs.openshift.com/container-platform/4.7/logging/cluster-logging-upgrading.html
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 26 May 2021 · Last source change 3 Aug 2024, 23:42 UTC · CWE-835 · Loop with Unreachable Exit Condition ('Infinite Loop')

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 2026-08-14
European sourceENISA EUVD · EUVD-2022-3094
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceNIST NVD
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. 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 OpenShift Container Platform 4.9 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this errata update: https://docs.openshift.com/container-platform/4.9/release_notes/ocp-4-9-release-notes.html For Red Hat OpenShift Logging 5.3, see the following instructions to apply this update: https://docs.openshift.com/container-platform/4.7/logging/cluster-logging-upgrading.html
    Red Hat Product Security ↗
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
ENISA EUVD · EUVD-2022-3094↗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-2021-33194 · cve.blacktree.nl