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.

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Mon, 26 Oct 2026 20:45:00 +0000

Type Values Removed Values Added
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.
Title Autobahn Python: permessage-brotli inflates a whole frame before maxMessagePayloadSize is checked (incomplete fix of GHSA-hxp9-w8x3-p566)
Weaknesses CWE-409
CWE-770
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-26T20:29:22.906Z

Reserved: 2026-10-26T15:03:39.035Z

Link: CVE-2026-116579

cve-icon Vulnrichment

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cve-icon NVD

Status : Received

Published: 2026-10-26T21:18:15.117

Modified: 2026-10-26T21:18:15.117

Link: CVE-2026-116579

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses