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Full vulnerability report · 2021
CVE-2021-21419High confidence

Improper Handling of Highly Compressed Data (Data Amplification) and Memory Allocation with Excessive Size Value in eventlet

eventlet · eventlet

Official source article: GitHub GHSA-9P9M-JM8W-94P2 ↗. Check the applicable product and release in the original source.

5.3MediumCVSS 3.1
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, 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 1.79% 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 eventlet eventlet 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: As exposure requiresRemediation target: Within 365 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 · sourcepython-eventletVendor fix publishedDebian records a fixed source-package version for this release.0.26.1-7Debian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourcepython-eventletVendor fix publishedDebian records a fixed source-package version for this release.0.26.1-7Debian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourcepython-eventletVendor fix publishedDebian records a fixed source-package version for this release.0.26.1-7Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcepython-eventletVendor fix publishedDebian records a fixed source-package version for this release.0.26.1-7Debian 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-2021-21419 · CSAF 2.0 · revision 3 · status not statedRed Hat Product Securitypython-eventlet: improper handling of highly compressed data and memory allocation with excessive size allows DoS
5 known affected

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

  • python-eventlet.src as a component of Red Hat OpenStack Platform 10 (Newton)
  • python-eventlet.src as a component of Red Hat OpenStack Platform 13 (Queens)
  • python-eventlet as a component of Red Hat Storage 3
  • python-eventlet-doc as a component of Red Hat Storage 3
  • python-eventlet.src as a component of Red Hat Storage 3
Summary
A flaw was found in eventlet. If an unauthenticated user manages to send large websocket frames or highly compressed data frames that can lead to memory exhaustion. An attacker could use this flaw to cause a denial of service (DoS).
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
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-2021-0072

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 actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
01

What, why and how

Eventlet is a concurrent networking library for Python. A websocket peer may exhaust memory on Eventlet side by sending very large websocket frames. Malicious peer may exhaust memory on Eventlet side by sending highly compressed data frame. A patch in version 0.31.0 restricts websocket frame to reasonable limits. As a workaround, restricting memory usage via OS limits would help against overall machine exhaustion, but there is no workaround to protect Eventlet process.

What

Eventlet is a concurrent networking library for Python. A websocket peer may exhaust memory on Eventlet side by sending very large websocket frames. Malicious peer may exhaust memory on Eventlet side by sending highly compressed data frame. A patch in version 0.31.0 restricts websocket frame to reasonable limits. As a workaround, restricting memory usage via OS limits would help against overall machine exhaustion, but there is no workaround to protect Eventlet process.

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 cause the confidentiality, integrity or availability impact described by the vendor.

What

Eventlet is a concurrent networking library for Python. A websocket peer may exhaust memory on Eventlet side by sending very large websocket frames. Malicious peer may exhaust memory on Eventlet side by sending highly compressed data frame. A patch in version 0.31.0 restricts websocket frame to reasonable limits. As a workaround, restricting memory usage via OS limits would help against overall machine exhaustion, but there is no workaround to protect Eventlet process.

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 cause the confidentiality, integrity or availability impact described by the vendor.

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 → cause the confidentiality, integrity or availability impact described by the vendor
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:L

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.ALowAvailability impact: A successful attack can cause a limited 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.
NetworkUnauthenticatedCWE-400
A

Official authority intelligence

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

BSI · German · WID-SEC-2023-0395Splunk Splunk Enterprise: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Splunk Splunk Enterprise ausnutzen, um vertrauliche Informationen offenzulegen, Sicherheitsmaßnahmen zu umgehen, einen Denial-of-Service-Zustand zu verursachen, Daten zu manipulieren und einen Cross-Site-Scripting-Angriff durchzuführen.

Official advisory ↗
BSI · German · WID-SEC-2024-0103Red Hat OpenStack: Schwachstelle ermöglicht Denial of Service

Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Red Hat OpenStack ausnutzen, um einen Denial of Service Angriff durchzuführen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20210512Security Bulletin 12 May 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 12 May 2021, published on 12 May 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2023-AVI-0142Multiples vulnérabilités dans les produits Splunk

sécurité Splunk SVD-2023-0202 du 14 février 2023 https://advisory.splunk.com/advisories/SVD-2023-0202 Bulletin de sécurité Splunk SVD-2023-0203 du 14 février 2023 https://advisory.splunk.com/advisories/SVD-2023-0203 Bulletin de sécurité Splunk SVD-2023-0205 du 14 février 2023 https://advisory.splunk.com/advisories/SVD-2023-0205 Bulletin de sécurité Splunk SVD-2023-0210 du 14 février 2023 https://advisory.splunk.com/advisories/SVD-2023-0210 Bulletin de sécurité Splunk SVD-2023-0215 du 14 février 2023 https://advisory.splunk.com/advisories/SVD-2023-0215 Référence CVE CVE-2015-20107 https://www.cve.org/CVERecord?id=CVE-2015-20107 Référence CVE CVE-2021-21419 https://www.cve.org/CVERecord?id=CVE-2021-21419 Référence CVE CVE-2021-28957 https://www.cve.org/CVERecord?id=CVE-2021-28957 Référence CVE CVE-2021-3517 https://www.cve.org/CVERecord?id=CVE-2021-3517 Référence CVE CVE-2021-3518 https://www.cve.org/CVERecord?id=CVE-2021-3518 Référence CVE CVE-2021-3537 https://www.cve.org/CVERecord?id=CVE-2021-3537 Référence CVE CVE-2022-24785 https://www.cve.org/CVERecord?id=CVE-2022-24785 Référence CVE CVE-2022-31129 https://www.cve.org/CVERecord?id=CVE-2022-31129 Référence CVE CVE-2022-32212 https://www.cve.org/CVERecord?id=CVE-2022-32212 Référence CVE CVE-2023-22931 https://www.cve.org/CVERecord?id=CVE-20

Official advisory ↗
CERT-FR · French · CERTFR-2022-AVI-417Multiples vulnérabilités dans les produits Aruba

s ont été découvertes dans les produits Aruba. Certaines d'entre elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance, un contournement de la politique de sécurité et une atteinte à la confidentialité des données. Solution Se référer au bulletin de sécurité de l'éditeur pour l'obtention des correctifs (cf. section Documentation). Documentation Bulletin de sécurité Aruba ARUBA-PSA-2022-007 du 04 mai 2022 https://www.arubanetworks.com/assets/alert/ARUBA-PSA-2022-007.txt Bulletin de sécurité Aruba ARUBA-PSA-2022-009 du 04 mai 2022 https://www.arubanetworks.com/assets/alert/ARUBA-PSA-2022-009.txt Référence CVE CVE-2021-21419 https://www.cve.org/CVERecord?id=CVE-2021-21419 Référence CVE CVE-2021-23665 https://www.cve.org/CVERecord?id=CVE-2021-23665 Référence CVE CVE-2021-33503 https://www.cve.org/CVERecord?id=CVE-2021-33503 Référence CVE CVE-2022-0778 https://www.cve.org/CVERecord?id=CVE-2022-0778 Référence CVE CVE-2022-23657 https://www.cve.org/CVERecord?id=CVE-2022-23657 Référence CVE CVE-2022-23658 https://www.cve.org/CVERecord?id=CVE-2022-23658 Référence CVE CVE-2022-23659 https://www.cve.org/CVERecord?id=CVE-2022-23659 Référence CVE CVE-2022-23660 https://www.cve.org/CVERecord?id=CVE-2022-23660 Référence CVE CVE-2022-23661 https://www.cve.org/CVERecord?id=CV

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-006548Eventlet におけるリソースの枯渇に関する脆弱性

Eventlet には、リソースの枯渇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 details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
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 7 May 2021 · Last source change 3 Aug 2024, 18:09 UTC · CWE-400 · Uncontrolled Resource Consumption

CVE recordCVE.org · 5.1
CVSS sourceCNA
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-2021-0072
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    >= 0.10, < 0.31.0 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    >= 0.10, < 0.31.0 · 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
    Red Hat Product Security ↗
  2. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    Red Hat Product Security ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2021-0072↗Red Hat Product Security security advisory↗CVE authority or vendor reference · GitHub GHSA-9P9M-JM8W-94P2↗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-2021-21419 · cve.blacktree.nl