GitHub Advisoryadvisory · PyPI
GHSA-c427-h43c-vf67 AIOHTTP accepts duplicate Host headers
MEDIUM
Official page ↗
- Aliases
- CVE-2026-34525
- Ecosystem
- PyPI
- Packages
- aiohttp
- Severity
- Moderate
- CVSS vector
- 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
- Weaknesses
- CWE-20, CWE-444
- Reviewed
- 2026-04-01
Affected packages
• PyPI aiohttp: < 3.13.4 → fixed in 3.13.4
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()`.
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Patch: https://github.com/aio-libs/aiohttp/commit/e00ca3cca92c465c7913c4beb763a72da9ed8349
Patch: https://github.com/aio-libs/aiohttp/commit/53e2e6fc58b89c6185be7820bd2c9f40216b3000
Related
Alias · CVE (1)
- CVE-2026-34525 AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. vulnerability
References
- https://github.com/aio-libs/aiohttp/security/advisories/GHSA-c427-h43c-vf67 web
- https://nvd.nist.gov/vuln/detail/CVE-2026-34525 advisory
- https://github.com/aio-libs/aiohttp/commit/53e2e6fc58b89c6185be7820bd2c9f40216b3000 web
- https://github.com/aio-libs/aiohttp/commit/e00ca3cca92c465c7913c4beb763a72da9ed8349 web
- https://github.com/aio-libs/aiohttp package
- https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4 web