CVE-2026-34517
MEDIUM5.3EPSS 0.02%AIOHTTP has late size enforcement for non-file multipart fields causes memory DoS
Published: 4/1/2026Modified: 4/2/2026
Description
### Summary For some multipart form fields, aiohttp read the entire field into memory before checking client_max_size. ### Impact If an application uses `Request.post()` an attacker can send a specially crafted multipart request to force significant temporary memory allocation even when the request is ultimately rejected. ----- Patch: https://github.com/aio-libs/aiohttp/commit/cbb774f38330563422ca0c413a71021d7b944145
Affected packages (2)
- Debian/python-aiohttpfrom 0
- PyPI/aiohttpfrom 0, < 3.13.4
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:L/SC:N/SI:N/SA:N/E:U |
| osv | CVSS 3.1 | MEDIUM5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
References (6)
- ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2026-34517
- ADVISORYhttps://security-tracker.debian.org/tracker/CVE-2026-34517
- PATCHhttps://github.com/aio-libs/aiohttp
- WEBhttps://github.com/aio-libs/aiohttp/commit/cbb774f38330563422ca0c413a71021d7b944145
- WEBhttps://github.com/aio-libs/aiohttp/releases/tag/v3.13.4
- WEBhttps://github.com/aio-libs/aiohttp/security/advisories/GHSA-3wq7-rqq7-wx6j