{"cve":"CVE-2026-34520","nvd":{"published":"2026-04-01T21:17:00.333","modified":"2026-10-26T21:10:00.170","status":"Analyzed","description":"AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, the C parser (the default for most installs) accepted null bytes and control characters in response headers. This issue has been patched in version 3.13.4.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U","score":2.7},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","score":9.1},"cwes":["CWE-113"],"references":["https://github.com/aio-libs/aiohttp/commit/9370b9714a7a56003cacd31a9b4ae16eab109ba4","https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4","https://github.com/aio-libs/aiohttp/security/advisories/GHSA-63hf-3vf5-4wqf"],"products":["aiohttp:aiohttp"],"source":"nvd","synced_at":"2026-10-26T21:38:48.864438205+00:00"},"epss":{"cve":"CVE-2026-34520","score":0.00461,"percentile":0.39692,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-63hf-3vf5-4wqf","url":"https://osv.dev/vulnerability/GHSA-63hf-3vf5-4wqf","summary":"AIOHTTP's C parser (llhttp) accepts null bytes and control characters in response header values - header injection/security bypass","modified":"2026-09-10T03:50:43.255807027Z","packages":[{"ecosystem":"PyPI","name":"aiohttp","purl":"pkg:pypi/aiohttp","ranges":["<3.13.4"],"fixed":["3.13.4"]}]},{"id":"PYSEC-2026-2102","url":"https://osv.dev/vulnerability/PYSEC-2026-2102","summary":"","modified":"2026-07-13T07:15:12.708711382Z","packages":[{"ecosystem":"PyPI","name":"aiohttp","purl":"pkg:pypi/aiohttp","ranges":["<3.13.4"],"fixed":["3.13.4"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}