Medium 5.9Published Oct 26, 2026

CVE-2026-116579Autobahn Python: permessage-brotli inflates a whole frame before maxMessagePayloadSize is checked (incomplete fix of GHSA-hxp9-w8x3-p566)

Updated under an hour ago (Oct 28, 2026, 11:40 AM ET)

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Every CVE for crossbario autobahn-python

Exploited in the last 30 days

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.

CVSS: 5.9 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-409, CWE-770
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Awaiting Analysis
Record last updated: Oct 27, 2026
First seen by InfoSec Signals: Oct 26, 2026

Affected products

Affected products

crossbario autobahn-python crossbario:autobahn_python (from the name)	from 26.7.1, < 26.10.1	CNA record

References

References

https://github.com/crossbario/autobahn-python/security/advisories/GHSA-pjh6-c8mg-3x7m	x-refsource-confirm
https://github.com/crossbario/autobahn-python/pull/1987	x-refsource-misc
https://github.com/crossbario/autobahn-python/commit/a41442bbee4f6126a8ce1bb892840124c24d16f1	x-refsource-misc
https://github.com/crossbario/autobahn-python/releases/tag/v26_10_1	x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.