Answer in brief
CVE-2026-59881 records a Medium severity security vulnerability in AIOHTTP: WebSocket client accepts compressed frames without negotiated permessage-deflate. The source record does not mark it as known exploited. 1 affected package is mapped in the feed.
Answer in brief
CVE-2026-59881 records a Medium severity security vulnerability in AIOHTTP: WebSocket client accepts compressed frames without negotiated permessage-deflate. The source record does not mark it as known exploited. 1 affected package is mapped in the feed.
Update aiohttp to 3.14.2 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanVulnerability describes the vulnerability class recorded for this advisory. The current record does not mark CVE-2026-59881 as known exploited; continue to monitor the source for status changes. The feed includes package mappings that can be checked against lockfiles and deployed manifests.
| Package | Affected range | Fixed version |
|---|---|---|
| aiohttppip | <=3.14.1 | 3.14.2 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
CVE-2026-59881 records a Medium severity security vulnerability in AIOHTTP: WebSocket client accepts compressed frames without negotiated permessage-deflate. The source record does not mark it as known exploited. 1 affected package is mapped in the feed.
The source record does not mark it as known exploited.
Check lockfiles and deployed manifests for aiohttp.
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL GuardUpdate aiohttp to 3.14.2 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanVulnerability describes the vulnerability class recorded for this advisory. The current record does not mark CVE-2026-59881 as known exploited; continue to monitor the source for status changes. The feed includes package mappings that can be checked against lockfiles and deployed manifests.
| Package | Affected range | Fixed version |
|---|---|---|
| aiohttppip | <=3.14.1 | 3.14.2 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
CVE-2026-59881 records a Medium severity security vulnerability in AIOHTTP: WebSocket client accepts compressed frames without negotiated permessage-deflate. The source record does not mark it as known exploited. 1 affected package is mapped in the feed.
The source record does not mark it as known exploited.
Check lockfiles and deployed manifests for aiohttp.
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard### 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
### 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