PyPI/aiohttp CVE-2026-34520: critical 9.1, EPSS 0.48%
AIOHTTP's C parser (llhttp) accepts null bytes and control characters in response header values - header injection/security bypass
Action: Upgrade aiohttp to 3.13.4 or later.
pip install aiohttp==3.13.4Affected
| introduced | fixed | last affected |
|---|---|---|
| 0 | 3.13.4 | - |
Fixed versions
| 3.13.4 |
Sources
- osv: GHSA-63hf-3vf5-4wqf
- https://github.com/aio-libs/aiohttp/security/advisories/GHSA-63hf-3vf5-4wqf
- https://nvd.nist.gov/vuln/detail/CVE-2026-34520
- https://github.com/aio-libs/aiohttp/commit/9370b9714a7a56003cacd31a9b4ae16eab109ba4
- https://github.com/aio-libs/aiohttp
- https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4
- https://github.com/pypa/advisory-database/tree/main/vulns/aiohttp/PYSEC-2026-2102.yaml
CVE-2026-34520 · published · modified · JSON