Vulnerability · Published Apr 1, 2026 · Assigned by GitHub_M
CVE-2026-34517AIOHTTP: Late size enforcement for non-file multipart fields causes memory DoS
Low 2.7
In plain English
A low-severity resource allocation without limits in aiohttp from aio-libs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 4.0)2.7Low
Exploit odds (30 days)0.4%top 65.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, for some multipart form fields, aiohttp read the entire field into memory before checking client_max_size. This issue has been patched in version 3.13.4.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | py3-aiohttp | 3.13.5-r0 | ALPINE-CVE-2026-34517 |
| Alpine:v3.24 | py3-aiohttp | 3.13.5-r0 | ALPINE-CVE-2026-34517 |
| Debian:12 | python-aiohttp | 3.8.4-1+deb12u2 | DEBIAN-CVE-2026-34517 |
| Debian:13 | python-aiohttp | no fix listed | DEBIAN-CVE-2026-34517 |
| Debian:14 | python-aiohttp | 3.13.5-1 | DEBIAN-CVE-2026-34517 |
| PyPI | aiohttp | 3.13.4 | PYSEC-2026-2099 |
| PyPI | aiohttp | 3.13.4 | GHSA-3wq7-rqq7-wx6j |
| Ubuntu:25.10 | python-aiohttp | no fix listed | UBUNTU-CVE-2026-34517 |
| Ubuntu:26.10 | python-aiohttp | no fix listed | UBUNTU-CVE-2026-34517 |
Affected products (as reported)
Weakness: CWE-770 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
References
- https://github.com/aio-libs/aiohttp/security/advisories/GHSA-3wq7-rqq7-wx6j x_refsource_CONFIRM
- https://github.com/aio-libs/aiohttp/commit/cbb774f38330563422ca0c413a71021d7b944145 x_refsource_MISC
- https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4 x_refsource_MISC