CVE-2026-54277
aiohttp: C HTTP Parser Bypasses max_line_size for Fragmented Lines
Description
### Summary It is possible to bypass the max_line_size check in parts of an HTTP request in the C parser. ### Impact If using the optimised C parser (the default in pre-built wheels), then an attacker may be able to send oversized lines through the HTTP parser and use an excessive amount of memory, potentially leading to DoS. ----- Patch: https://github.com/aio-libs/aiohttp/commit/5ab61bb4cd88f19b712f12c7c9295fe262bf804d
How to fix CVE-2026-54277
To remediate CVE-2026-54277, upgrade the affected package to a fixed version below.
- PyPI/aiohttp—upgrade to 3.14.1 or later
Is CVE-2026-54277 being exploited?
No exploitation signal available. Neither CISA KEV nor a current EPSS score has been published for CVE-2026-54277.
Affected packages (1)
- from 0, < 3.14.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U |