CVSS 3.1
5.3 mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:LCVE-2026-77528
Medium (5.3). EPSS 0.5% chance of exploitation in the next 30 days. Fixed in autobahn 26.7.1.
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.
Severity
- EPSS
- 0.5% chance of exploitation in the next 30 days; higher than 44% of CVEs (scores of 2026-10-31)
- CWEs
- CWE-409, CWE-770
- Published
- Modified
- Record from
- the NVD, synced
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-hxp9-w8x3-p566 | PyPI | autobahn | <26.7.1 | 26.7.1 |
| GHSA-hxp9-w8x3-p566 | PyPI | crossbar | <26.7.1 | 26.7.1 |
| PYSEC-2026-4027 | PyPI | autobahn | <26.7.1 | 26.7.1 |
| PYSEC-2026-4031 | PyPI | crossbar | <26.7.1 | 26.7.1 |