{"id":"CVE-2026-34519","aliases":["GHSA-mwh4-6h8g-pg8w","PYSEC-2026-2101"],"url":"https://o3.security/vulnerability/CVE-2026-34519","summary":"AIOHTTP: HTTP response splitting via \\r in reason phrase","details":"### Summary\n\nAn attacker who controls the `reason` parameter when creating a `Response` may be able to inject extra headers or similar exploits.\n\n### Impact\n\nIn the unlikely situation that an application allows untrusted data to be used in the response's `reason` parameter, then an attacker could manipulate the response to send something different from what the developer intended.\n\n-----\n\nPatch: https://github.com/aio-libs/aiohttp/commit/53b35a2f8869c37a133e60bf1a82a1c01642ba2b","published":"2026-04-01T20:26:25.553Z","modified":"2026-10-28T02:31:15.035214807Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"aiohttp","fixedVersion":"3.13.4"}],"fix":{"url":"https://github.com/aio-libs/aiohttp/commit/53b35a2f8869c37a133e60bf1a82a1c01642ba2b","label":"aio-libs/aiohttp@53b35a2"},"references":[{"type":"WEB","url":"https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34519.json"},{"type":"ADVISORY","url":"https://github.com/aio-libs/aiohttp/security/advisories/GHSA-mwh4-6h8g-pg8w"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-34519"},{"type":"FIX","url":"https://github.com/aio-libs/aiohttp/commit/53b35a2f8869c37a133e60bf1a82a1c01642ba2b"},{"type":"PACKAGE","url":"https://github.com/aio-libs/aiohttp"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:31:15.035214807Z"}}