CVE-2026-128128
AIOHTTP: WebSocket max_msg_size bypass via integer overflow
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, the C WebSocket reader adds a declared frame length to the size of an already buffered partial message using signed 64-bit arithmetic. A length near two to the power of 63 can overflow, allowing the max_msg_size check to pass. A remote peer can send a small non-final fragment followed by an oversized message and cause unbounded memory consumption. The Python WebSocket reader is unaffected. This issue is fixed in version 3.14.4.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| aiohttp aio-libs |
< 3.14.4 (affected) | CNA: GitHub_M |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 7.5 high |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | CNA: GitHub_M |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/aio-libs/aiohttp/security/advisories/GHSA-3rp8-rxj8-mvjwCNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/aio-libs/aiohttp/pull/13415CNA: GitHub_M · x_refsource_MISC
- https://github.com/aio-libs/aiohttp/pull/13494CNA: GitHub_M · x_refsource_MISC
- https://github.com/aio-libs/aiohttp/commit/8c8906a19f64e52ef6a7d44d65217eb3c5af413fCNA: GitHub_M · x_refsource_MISC
- https://github.com/aio-libs/aiohttp/commit/8cfbe9abe5e11b84006a10f9bdf82bf607671dabCNA: GitHub_M · x_refsource_MISC
- https://github.com/aio-libs/aiohttp/releases/tag/v3.14.4CNA: GitHub_M · x_refsource_MISC
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