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Vulnerability · Published Apr 1, 2026 · Assigned by GitHub_M

CVE-2026-34518AIOHTTP: Cookie and Proxy-Authorization headers leaked on cross-origin redirect

Low 2.7

In plain English

A low-severity information exposure in aiohttp from aio-libs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)2.7Low
Exploit odds (30 days)0.4%top 71.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, when following redirects to a different origin, aiohttp drops the Authorization header, but retains the Cookie and Proxy-Authorization headers. This issue has been patched in version 3.13.4.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.23py3-aiohttp3.13.5-r0ALPINE-CVE-2026-34518
Alpine:v3.24py3-aiohttp3.13.5-r0ALPINE-CVE-2026-34518
Debian:12python-aiohttp3.8.4-1+deb12u2DEBIAN-CVE-2026-34518
Debian:13python-aiohttpno fix listedDEBIAN-CVE-2026-34518
Debian:14python-aiohttp3.13.5-1DEBIAN-CVE-2026-34518
PyPIaiohttp3.13.4PYSEC-2026-2100
PyPIaiohttp3.13.4GHSA-966j-vmvw-g2g9
Ubuntu:25.10python-aiohttpno fix listedUBUNTU-CVE-2026-34518
Ubuntu:26.10python-aiohttpno fix listedUBUNTU-CVE-2026-34518

Affected products (as reported)

VendorProductVersions
aio-libs aiohttp < 3.13.4

Weakness: CWE-200 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U

References