{"id":"CVE-2026-34518","aliases":["GHSA-966j-vmvw-g2g9","PYSEC-2026-2100"],"title":"AIOHTTP leaks Cookie and Proxy-Authorization headers on cross-origin redirect","summary":"AIOHTTP leaks Cookie and Proxy-Authorization headers on cross-origin redirect","severity":"medium","cvss":5.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","vendor":"aiohttp","product":"aiohttp","ecosystem":"pip","affected":["aiohttp < 3.13.4"],"patched":["aiohttp 3.13.4"],"published":"2026-04-01","updated":"2026-09-10","sourceUpdated":"2026-09-10T03:51:01.374434696Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-966j-vmvw-g2g9","references":[{"url":"https://github.com/aio-libs/aiohttp/security/advisories/GHSA-966j-vmvw-g2g9"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-34518"},{"url":"https://github.com/aio-libs/aiohttp/commit/5351c980dcec7ad385730efdf4e1f4338b24fdb6"},{"url":"https://github.com/aio-libs/aiohttp"},{"url":"https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4"}],"tags":["osv","pip"],"epss":0.00337,"epssPercentile":0.27212,"ingestedAt":"2026-07-13T18:57:55.709Z","slug":"CVE-2026-34518","body":"## Overview\n\n### Summary\n\nWhen following redirects to a different origin, aiohttp drops the Authorization header, but retains the Cookie and Proxy-Authorization headers.\n\n### Impact\n\nThe Cookie and Proxy-Authorizations headers could contain sensitive information which may be leaked to an unintended party after following a redirect.\n\n-----\n\nPatch: https://github.com/aio-libs/aiohttp/commit/5351c980dcec7ad385730efdf4e1f4338b24fdb6\n\n## Affected packages\n\n- `aiohttp < 3.13.4`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `aiohttp 3.13.4`","depth":"sunlit","depthScore":29,"depthScoreParts":{"impact":29.2,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}