{"id":"CVE-2026-123817","aliases":["GHSA-2g87-pp6c-29x5"],"title":"aiohttp: Multiple instances of excessive or unbounded memory/CPU use","summary":"aiohttp: Multiple instances of excessive or unbounded memory/CPU use","severity":"high","cvss":8.7,"cvssVector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","vendor":"aiohttp","product":"aiohttp","ecosystem":"pip","affected":["aiohttp < 3.14.4"],"patched":["aiohttp 3.14.4"],"published":"2026-10-19","updated":"2026-11-09","sourceUpdated":"2026-11-09T21:30:07.738926065Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-2g87-pp6c-29x5","references":[{"url":"https://github.com/aio-libs/aiohttp/security/advisories/GHSA-2g87-pp6c-29x5"},{"url":"https://github.com/aio-libs/aiohttp/commit/09bcaa73ff084a0c539bbf16a0a78743acb7141f"},{"url":"https://github.com/aio-libs/aiohttp/commit/0ae507423f681161efa77d20052b4054397c7fb6"},{"url":"https://github.com/aio-libs/aiohttp/commit/3d850ee9b92573c7e913821cbcb96005beb3f4df"},{"url":"https://github.com/aio-libs/aiohttp/commit/47babd8c23ca79e2bae6cc8dcb5752b61e369fc7"},{"url":"https://github.com/aio-libs/aiohttp/commit/615fec3d4f088f30d2ee72cad760152e92aa1c53"},{"url":"https://github.com/aio-libs/aiohttp/commit/6963ee0befec1502b6bb7b4db6c72d044c08f4fa"},{"url":"https://github.com/aio-libs/aiohttp/commit/6a4f6682817839313b04b8e5cea2b39c1a88ab4f"},{"url":"https://github.com/aio-libs/aiohttp/commit/8cfbe9abe5e11b84006a10f9bdf82bf607671dab"},{"url":"https://github.com/aio-libs/aiohttp/commit/a555ab698e08e9baea7386d5b4c0761cb8956fdd"},{"url":"https://github.com/aio-libs/aiohttp/commit/c6ac0e44c3c573ff9616f4a6a532992538b31e43"},{"url":"https://github.com/aio-libs/aiohttp/commit/d925a80539ffd227da1d93ab4a5bff123cc777db"},{"url":"https://github.com/aio-libs/aiohttp"},{"url":"https://github.com/aio-libs/aiohttp/releases/tag/v3.14.4"},{"url":"https://github.com/advisories/GHSA-2g87-pp6c-29x5"},{"url":"https://github.com/aio-libs/aiohttp/pull/13352","label":"https://github.com/aio-libs/aiohttp/pull/13352"},{"url":"https://github.com/aio-libs/aiohttp/pull/13612","label":"https://github.com/aio-libs/aiohttp/pull/13612"}],"tags":["osv","pip","ghsa","cve.org"],"epss":0.00328,"epssPercentile":0.26109,"cvssSource":"cna","cwe":["CWE-770"],"ingestedAt":"2026-11-09T21:28:49.531Z","slug":"CVE-2026-123817","body":"## Overview\n\n### Summary\n\nWhile reassembling a WebSocket frame that arrived across many small transport reads, the reader kept one `bytes` object per read with no bound on the count. The per-object overhead is many times larger than the payload bytes, so a frame delivered a few bytes at a time could use far more memory than `max_msg_size` allows.\n\n### Impact\n\nAn attacker could cause excessive memory use in a WebSocket server, or a malicious server against a client, by sending a frame in a large number of tiny segments.\n\n## Affected packages\n\n- `aiohttp < 3.14.4`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `aiohttp 3.14.4`","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":47.8,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}