{"cve":"CVE-2021-21419","nvd":{"published":"2021-05-07T15:15:07.407","modified":"2026-06-17T03:35:32.337","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3},"cwes":["CWE-400"],"references":["https://github.com/eventlet/eventlet/security/advisories/GHSA-9p9m-jm8w-94p2","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-94p2","https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2WJFSBPLCNSZNHYQC4QDRDFRTEZRMD2L/"],"products":["eventlet:eventlet","fedoraproject:fedora"],"source":"nvd","synced_at":"2026-10-19T21:18:09.669877188+00:00"},"epss":{"cve":"CVE-2021-21419","score":0.01792,"percentile":0.78393,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-9p9m-jm8w-94p2","url":"https://osv.dev/vulnerability/GHSA-9p9m-jm8w-94p2","summary":"Improper Handling of Highly Compressed Data (Data Amplification) and Memory Allocation with Excessive Size Value in eventlet","modified":"2026-07-08T06:27:42.178135165Z","packages":[{"ecosystem":"PyPI","name":"eventlet","purl":"pkg:pypi/eventlet","ranges":[">=0.10 <0.31.0"],"fixed":["0.31.0"]}]},{"id":"PYSEC-2021-12","url":"https://osv.dev/vulnerability/PYSEC-2021-12","summary":"","modified":"2023-11-08T04:04:45.339697Z","packages":[{"ecosystem":"PyPI","name":"eventlet","purl":"pkg:pypi/eventlet","ranges":[">=0.10.0 <0.31.0"],"fixed":["0.31.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}