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CVE-2026-116579GHSA-pjh6-c8mg-3x7m

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

crossbario autobahn-pythonRuntimes & languages
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CVSS
5.9Medium
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)No scoreNo FIRST EPSS score in this snapshot yet
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
Published26 Oct 2026Updated 26 Oct 2026CVE List

What fixes it

No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.

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.

Text from CVE List

Affected versions 1

  • autobahn-pythonaffected: >= 26.7.1, < 26.10.1CVE List

References 4