Answer in brief
CVE-2026-77528 records a Medium severity (CVSS 5.3) vulnerability in Autobahn Python permessage-deflate bypasses maxMessagePayloadSize after inflation. The current sources do not mark it as known exploited. The current feed maps crossbario/autobahn-python (generic), autobahn (pip), crossbar (pip), autobahn (pypi) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps crossbario/autobahn-python (generic), autobahn (pip), crossbar (pip), autobahn (pypi) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| crossbario/autobahn-pythongeneric | <26.7.1 | 26.7.1 |
| autobahnpip | <26.7.1 | 26.7.1 |
| crossbarpip | <26.7.1 | 26.7.1 |
| autobahnpypi | >=0 <26.7.1 | 26.7.1 |
| crossbarpypi | >=0 <26.7.1 | 26.7.1 |
Published upstream
Sep 18, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 24, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 18, 2026
Autobahn Python is a WebSocket and WAMP implementation for Python that supports Twisted and asyncio. Prior to 26.7.1, WebSocket endpoints that accept permessage-deflate and rely on maxMessagePayloadSize enforce that limit against the compressed frame length before inflation but do not recheck the decompressed message size before delivery. A remote unauthenticated client can send a valid compressed frame below the configured wire-size limit that expands beyond the application message limit, causing oversized data to be allocated, joined, validated, and passed to application callbacks. This can create resource-exhaustion pressure, but the advisory does not establish confidentiality or integrity impact. This issue is fixed in version 26.7.1.
Quoted source text, attributed separately from HOL analysis.