CVE-2026-116579 Autobahn Python: permessage-brotli inflates a whole frame before maxMessagePayloadSize is checked (incomplete fix of GHSA-hxp9-w8x3-p566)
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-116579?
CVE-2026-116579 is a medium-severity vulnerability in crossbario autobahn-python, published on 26 Oct 2026.
Official 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.
Which versions are affected by CVE-2026-116579?
2 open source packages ship an affected version, including autobahn.
| Package | Affected | Fixed in |
|---|---|---|
autobahn PyPI | From 26.7.1 | 26.10.1 |
autobahn PyPI | From 26.7.1 | 26.10.1 |
How do I fix CVE-2026-116579?
Upgrade autobahn to 26.10.1 or later.
Is CVE-2026-116579 being exploited?
There is no known exploitation of CVE-2026-116579 in the wild and no public exploit code.
Sources
Also known as GHSA-pjh6-c8mg-3x7m, UBUNTU-CVE-2026-116579.