Answer in brief
CVE-2026-59881 records a Medium severity vulnerability in AIOHTTP: WebSocket client accepts compressed frames without negotiated permessage-deflate. The current sources do not mark it as known exploited. The current feed maps aiohttp (pip), aiohttp (pypi). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps aiohttp (pip), aiohttp (pypi). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| aiohttppip | <=3.14.1 | 3.14.2 |
| aiohttppypi | >=0 <3.14.2 | 3.14.2 |
Published upstream
Aug 3, 2026
Evidence: source:ghsa:source_dates:source-dates:recordSource modified
Sep 10, 2026
Evidence: source:ghsa:source_dates:source-dates:recordFirst seen by HOL
Aug 3, 2026
### Summary The client accepts and decompresses frames with the RSV1 bit set even when the `permessage-deflate` extension was not negotiated. ### Impact A client may unexpectedly decompress WebSocket frames when explicitly opted out. This could lead to additional CPU/memory consumption, but is unlikely to be a significant issue unless a zip bomb vulnerability or similar is also present. --- Patch: https://github.com/aio-libs/aiohttp/commit/47fb6ae354d4fa22048f4dbe7dbf82b625f0a2f6
Quoted source text, attributed separately from HOL analysis.