VulnerabilityAnalyzed

CVE-2026-34516

Prior to version 3.13.4, a response with an excessive number of multipart headers may be allowed to use more memory than intended, potentially allowing a DoS vulnerability.

MEDIUM 6.6EPSS 0.44%

Does this matter?

Lower severity and a low EPSS score (0.44%). Track it; it rarely justifies an emergency change on its own.

Description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, a response with an excessive number of multipart headers may be allowed to use more memory than intended, potentially allowing a DoS vulnerability. This issue has been patched in version 3.13.4.

CVSS 4.0: 6.6 MEDIUMCVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.44% probability · 37th percentile
CISA KEV: Not listed
Weakness: CWE-770
Affected: aiohttp/aiohttp
Source: security-advisories@github.com

References

https://github.com/aio-libs/aiohttp/commit/8a74257b3804c9aac0bf644af93070f68f6c5a6fPatch
https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4Release Notes
https://github.com/aio-libs/aiohttp/security/advisories/GHSA-m5qp-6w8w-w647Patch, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.