{"id":"PYSEC-2026-2102","details":"AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, the C parser (the default for most installs) accepted null bytes and control characters in response headers. This issue has been patched in version 3.13.4.","aliases":["CVE-2026-34520","GHSA-63hf-3vf5-4wqf"],"modified":"2026-07-13T07:15:12.708711382Z","published":"2026-04-01T21:17:00.333Z","references":[{"type":"ADVISORY","url":"https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4"},{"type":"FIX","url":"https://github.com/aio-libs/aiohttp/commit/9370b9714a7a56003cacd31a9b4ae16eab109ba4"},{"type":"FIX","url":"https://github.com/aio-libs/aiohttp/security/advisories/GHSA-63hf-3vf5-4wqf"}],"affected":[{"package":{"name":"aiohttp","ecosystem":"PyPI","purl":"pkg:pypi/aiohttp"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.13.4"}]}],"versions":["0.1","0.10.0","0.10.1","0.10.2","0.11.0","0.12.0","0.13.0","0.13.1","0.14.0","0.14.1","0.14.2","0.14.3","0.14.4","0.15.0","0.15.1","0.15.2","0.15.3","0.16.0","0.16.1","0.16.2","0.16.3","0.16.4","0.16.5","0.16.6","0.17.0","0.17.1","0.17.2","0.17.3","0.17.4","0.18.0","0.18.1","0.18.2","0.18.3","0.18.4","0.19.0","0.2","0.20.0","0.20.1","0.20.2","0.21.0","0.21.1","0.21.2","0.21.4","0.21.5","0.21.6","0.22.0","0.22.0a0","0.22.0b0","0.22.0b1","0.22.0b2","0.22.0b3","0.22.0b4","0.22.0b5","0.22.0b6","0.22.1","0.22.2","0.22.3","0.22.4","0.22.5","0.3","0.4","0.4.1","0.4.2","0.4.3","0.4.4","0.5.0","0.6.0","0.6.1","0.6.2","0.6.3","0.6.4","0.6.5","0.7.0","0.7.1","0.7.2","0.7.3","0.8.0","0.8.1","0.8.2","0.8.3","0.8.4","0.9.0","0.9.1","0.9.2","0.9.3","1.0.0","1.0.1","1.0.2","1.0.3","1.0.5","1.1.0","1.1.1","1.1.2","1.1.3","1.1.4","1.1.5","1.1.6","1.2.0","1.3.0","1.3.1","1.3.2","1.3.3","1.3.4","1.3.5","2.0.0","2.0.0rc1","2.0.1","2.0.2","2.0.3","2.0.4","2.0.5","2.0.6","2.0.7","2.1.0","2.2.0","2.2.1","2.2.2","2.2.3","2.2.4","2.2.5","2.3.0","2.3.0a1","2.3.0a2","2.3.0a3","2.3.0a4","2.3.1","2.3.10","2.3.1a1","2.3.2","2.3.2b2","2.3.2b3","2.3.3","2.3.4","2.3.5","2.3.6","2.3.7","2.3.8","2.3.9","3.0.0","3.0.0b0","3.0.0b1","3.0.0b2","3.0.0b3","3.0.0b4","3.0.1","3.0.2","3.0.3","3.0.4","3.0.5","3.0.6","3.0.7","3.0.8","3.0.9","3.1.0","3.1.1","3.1.2","3.1.3","3.10.0","3.10.0b1","3.10.0rc0","3.10.1","3.10.10","3.10.11","3.10.11rc0","3.10.2","3.10.3","3.10.4","3.10.5","3.10.6","3.10.6rc0","3.10.6rc1","3.10.6rc2","3.10.7","3.10.8","3.10.9","3.11.0","3.11.0b0","3.11.0b1","3.11.0b2","3.11.0b3","3.11.0b4","3.11.0b5","3.11.0rc0","3.11.0rc1","3.11.0rc2","3.11.1","3.11.10","3.11.11","3.11.12","3.11.13","3.11.14","3.11.15","3.11.16","3.11.17","3.11.18","3.11.2","3.11.3","3.11.4","3.11.5","3.11.6","3.11.7","3.11.8","3.11.9","3.12.0","3.12.0b0","3.12.0b1","3.12.0b2","3.12.0b3","3.12.0rc0","3.12.0rc1","3.12.1","3.12.10","3.12.11","3.12.12","3.12.13","3.12.14","3.12.15","3.12.1rc0","3.12.2","3.12.3","3.12.4","3.12.6","3.12.7","3.12.7rc0","3.12.8","3.12.9","3.13.0","3.13.1","3.13.2","3.13.3","3.2.0","3.2.1","3.3.0","3.3.0a0","3.3.1","3.3.2","3.3.2a0","3.4.0","3.4.0a0","3.4.0a3","3.4.0b1","3.4.0b2","3.4.1","3.4.2","3.4.3","3.4.4","3.5.0","3.5.0a1","3.5.0b1","3.5.0b2","3.5.0b3","3.5.1","3.5.2","3.5.3","3.5.4","3.6.0","3.6.0a0","3.6.0a1","3.6.0a11","3.6.0a12","3.6.0a2","3.6.0a3","3.6.0a4","3.6.0a5","3.6.0a6","3.6.0a7","3.6.0a8","3.6.0a9","3.6.0b0","3.6.1","3.6.1b3","3.6.1b4","3.6.2","3.6.2a0","3.6.2a1","3.6.2a2","3.6.3","3.7.0","3.7.0b0","3.7.0b1","3.7.1","3.7.2","3.7.3","3.7.4","3.7.4.post0","3.8.0","3.8.0a7","3.8.0b0","3.8.1","3.8.2","3.8.3","3.8.4","3.8.5","3.8.6","3.9.0","3.9.0b0","3.9.0b1","3.9.0rc0","3.9.1","3.9.2","3.9.3","3.9.4","3.9.4rc0","3.9.5"],"ecosystem_specific":{},"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/aiohttp/PYSEC-2026-2102.yaml"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"}]}