Improper Handling of Highly Compressed Data (Data Amplification) and Memory Allocation with Excessive Size Value in eventlet
Impact
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.
Patches
Version 0.31.0 restricts websocket frame to reasonable limits.
Workarounds
Restricting memory usage via OS limits would help against overall machine exhaustion. No workaround to protect Eventlet process.
For more information
If you have any questions or comments about this advisory:
- Open an issue in eventlet
- Contact current maintainers. At 2021-03: temotor@gmail.com or https://t.me/temotor
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | eventlet | >= 0.10, < 0.31.0 | 0.31.0 |
References
- https://github.com/eventlet/eventlet/security/advisories/GHSA-9p9m-jm8w-94p2
- https://nvd.nist.gov/vuln/detail/CVE-2021-21419
- https://github.com/eventlet/eventlet/commit/1412f5e4125b4313f815778a1acb4d3336efcd07
- https://github.com/eventlet/eventlet
- https://github.com/pypa/advisory-database/tree/main/vulns/eventlet/PYSEC-2021-12.yaml
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2WJFSBPLCNSZNHYQC4QDRDFRTEZRMD2L
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/R5JZP4LZOSP7CUAM3GIRW6PIAWKH5VGB
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L- Weakness (CWE)
CWE-400- Platform
- Python (PyPI)
- Package
eventlet- Disclosed
- 07.05.2021
- Updated
- 11.10.2026 13:19
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2021-12 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-9p9m-jm8w-94p2 - CC BY 4.0
Vulnerability history: eventlet
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 3
- First → latest
- 05.2021 08.2025
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 3
Disclosures per year
- 2021: 1
- 2022: 0
- 2023: 0
- 2024: 1
- 2025: 1
- 2026: 0
-
Improper Handling of Highly Compressed Data (Data Amplification) and Memory Allocation with Excessive Size Value in eventlet this entry
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