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.
Published: 2026-10-26
Score: 5.9 Medium
EPSS: < 1% Very Low
KEV: No
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Remediation

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History

Tue, 27 Oct 2026 15:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 27 Oct 2026 12:30:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Tue, 27 Oct 2026 04:30:00 +0000

Type Values Removed Values Added
First Time appeared Crossbario
Crossbario autobahn-python
Vendors & Products Crossbario
Crossbario autobahn-python

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'}


Subscriptions

Crossbario Autobahn-python
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-27T14:18:18.772Z

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

Link: CVE-2026-116579

cve-icon Vulnrichment

Updated: 2026-10-27T13:41:52.115Z

cve-icon NVD

Status : Awaiting Analysis

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

Modified: 2026-10-27T16:03:45.247

Link: CVE-2026-116579

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-10-26T20:29:22Z

Links: CVE-2026-116579 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-27T03:00:08Z

Weaknesses
  • CWE-409

    Improper Handling of Highly Compressed Data (Data Amplification)

  • CWE-770

    Allocation of Resources Without Limits or Throttling