Description
Autobahn Python is a WebSocket and WAMP implementation for Python that supports Twisted and asyncio. From 26.7.1 until 26.10.1, PerMessageBrotli.decompress_message_data in compress_brotli.py calls the Brotli decompressor without an output limit and checks maxMessagePayloadSize only after a complete frame has been inflated. An unauthenticated WebSocket client can send a small, highly compressed frame that allocates hundreds of MiB before rejection, causing memory-exhaustion denial of service on servers that enable the opt-in permessage-brotli feature through the compress extra. Deflate and bzip2 already enforce the remaining output budget and are outside this residual vulnerability. This issue is fixed in version 26.10.1.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HWeakness enumeration
Affected software
Source: the vendor's advisory (CNA). NVD analysis pending.
| Vendor | Product | Versions |
|---|---|---|
| crossbario | autobahn-python | >= 26.7.1, < 26.10.1 |
References
- https://github.com/crossbario/autobahn-python/commit/a41442bbee4f6126a8ce1bb892840124c24d16f1
- https://github.com/crossbario/autobahn-python/pull/1987
- https://github.com/crossbario/autobahn-python/releases/tag/v26_10_1
- https://github.com/crossbario/autobahn-python/security/advisories/GHSA-pjh6-c8mg-3x7m
Timeline
- Published
- Oct 26, 2026
- Last modified
- Oct 27, 2026
- NVD status
- Awaiting Analysis