aio-libs/aiohttp · Security
AIOHTTP accepts duplicate Host headers
- GHSA ID
- GHSA-c427-h43c-vf67
- CVE ID
- CVE-2026-34525
- Severity
- medium
- Published
- Updated
- CVSS v4
- 6.3 · CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N
Description
Summary
Multiple Host headers were allowed in aiohttp.
Impact
Mostly this doesn't affect aiohttp security itself, but if a reverse proxy is applying security rules depending on the target Host, it is theoretically possible that the proxy and aiohttp could process different host names, possibly resulting in bypassing a security check on the proxy and getting a request processed by aiohttp in a privileged sub app when using Application.add_domain().
Patch: https://github.com/aio-libs/aiohttp/commit/e00ca3cca92c465c7913c4beb763a72da9ed8349 Patch: https://github.com/aio-libs/aiohttp/commit/53e2e6fc58b89c6185be7820bd2c9f40216b3000
CWEs
- CWE-20 · Improper Input Validation
- CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
References
- https://github.com/aio-libs/aiohttp/security/advisories/GHSA-c427-h43c-vf67 ↗
- https://nvd.nist.gov/vuln/detail/CVE-2026-34525 ↗
- https://github.com/aio-libs/aiohttp/commit/53e2e6fc58b89c6185be7820bd2c9f40216b3000 ↗
- https://github.com/aio-libs/aiohttp/commit/e00ca3cca92c465c7913c4beb763a72da9ed8349 ↗
- https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4 ↗
- https://github.com/advisories/GHSA-c427-h43c-vf67 ↗