{"id":"CVE-2026-116579","title":"Autobahn Python: permessage-brotli inflates a whole frame before maxMessagePayloadSize is checked (incomplete fix of GHSA-hxp9-w8x3-p566)","summary":"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 outpu…","severity":"medium","cvss":5.9,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"cna","cwe":["CWE-409","CWE-770"],"vendor":"crossbario","product":"autobahn-python","affected":["autobahn-python >= 26.7.1, < 26.10.1"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-10-27T13:41:50.957164Z"},"published":"2026-10-26","updated":"2026-10-27","sourceUpdated":"2026-10-27T14:18:18.772Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-116579","references":[{"url":"https://github.com/crossbario/autobahn-python/security/advisories/GHSA-pjh6-c8mg-3x7m","label":"https://github.com/crossbario/autobahn-python/security/advisories/GHSA-pjh6-c8mg-3x7m"},{"url":"https://github.com/crossbario/autobahn-python/pull/1987","label":"https://github.com/crossbario/autobahn-python/pull/1987"},{"url":"https://github.com/crossbario/autobahn-python/commit/a41442bbee4f6126a8ce1bb892840124c24d16f1","label":"https://github.com/crossbario/autobahn-python/commit/a41442bbee4f6126a8ce1bb892840124c24d16f1"},{"url":"https://github.com/crossbario/autobahn-python/releases/tag/v26_10_1","label":"https://github.com/crossbario/autobahn-python/releases/tag/v26_10_1"}],"tags":["cve.org"],"epss":0.00425,"epssPercentile":0.36588,"ingestedAt":"2026-10-26T20:39:42.614Z","slug":"CVE-2026-116579","body":"## Overview\n\nAutobahn 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.\n\n## Affected\n\n- `autobahn-python >= 26.7.1, < 26.10.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":33,"depthScoreParts":{"impact":32.5,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}