{"id":"CVE-2021-21419","aliases":["GHSA-9p9m-jm8w-94p2","PYSEC-2021-12"],"url":"https://o3.security/vulnerability/CVE-2021-21419","summary":"Improper Handling of Highly Compressed Data (Data Amplification) and Memory Allocation with Excessive Size Value in eventlet","details":"### Impact\nA 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.\n\n### Patches\nVersion 0.31.0 restricts websocket frame to reasonable limits.\n\n### Workarounds\nRestricting memory usage via OS limits would help against overall machine exhaustion. No workaround to protect Eventlet process.\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [eventlet](https://github.com/eventlet/eventlet/issues)\n* Contact current maintainers. At 2021-03: temotor@gmail.com or https://t.me/temotor","published":"2021-05-07T15:15:07.407Z","modified":"2026-07-08T06:27:02.326657839Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"},"epss":{"score":0.01807,"percentile":0.76581,"asOf":"2026-08-23"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"eventlet","fixedVersion":"0.31.0"}],"fix":{"url":"https://github.com/eventlet/eventlet/commit/1412f5e4125b4313f815778a1acb4d3336efcd07","label":"eventlet/eventlet@1412f5e"},"references":[{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2WJFSBPLCNSZNHYQC4QDRDFRTEZRMD2L/"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/R5JZP4LZOSP7CUAM3GIRW6PIAWKH5VGB/"},{"type":"ADVISORY","url":"https://github.com/eventlet/eventlet/security/advisories/GHSA-9p9m-jm8w-94p2"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-21419"},{"type":"WEB","url":"https://github.com/eventlet/eventlet/commit/1412f5e4125b4313f815778a1acb4d3336efcd07"},{"type":"PACKAGE","url":"https://github.com/eventlet/eventlet"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/eventlet/PYSEC-2021-12.yaml"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2WJFSBPLCNSZNHYQC4QDRDFRTEZRMD2L"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/R5JZP4LZOSP7CUAM3GIRW6PIAWKH5VGB"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-08T06:27:02.326657839Z"}}