HOMEVULNERABILITIESCVE-2021-21419
MEDIUM

CVE-2021-21419

CWE-400Published: May 7, 2021· Updated: Jun 17, 2026

5.3
CVSS v3.1

Official Description

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.

NVD Source

Technical Analysis

CVE-2021-21419 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityLow
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected Vendors & Products

eventlet1 product(s)
eventlet
Fedora1 product(s)
fedora
Source: NVD CPE · 3 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://github.com/eventlet/eventlet/security/advisories/GHSA-9p9m-jm8w-94p2
ADVISORYhttps://github.com/eventlet/eventlet/security/advisories/GHSA-9p9m-jm8w-94p2

All References (6)

→
https://github.com/eventlet/eventlet/security/advisories/GHSA-9p9m-jm8w-94p2Third Party Advisory
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2WJFSBPLCNSZNHYQC4QDRDFRTEZRMD2L/
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/R5JZP4LZOSP7CUAM3GIRW6PIAWKH5VGB/
→
https://github.com/eventlet/eventlet/security/advisories/GHSA-9p9m-jm8w-94p2Third Party Advisory
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2WJFSBPLCNSZNHYQC4QDRDFRTEZRMD2L/
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/R5JZP4LZOSP7CUAM3GIRW6PIAWKH5VGB/

Quick Facts

CVE IDCVE-2021-21419
CVSS Score5.3 / 10
SeverityMEDIUM
WeaknessCWE-400
CISA KEVNo
Affected2 vendor(s)
PublishedMay 7, 2021

Related CVEs (CWE-400)

CVE-2015-4412
9.8
CVE-2013-20004
9.8
CVE-2025-43193
9.8
CVE-2017-1000378
9.8
CVE-2017-9119
9.8
CVE-2025-24190
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-21419 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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