CVE-2026-42544 json
Granian: Unauthenticated DoS via WebSocket subprotocol header panic
published 2026-05-06 6 mo ago modified 2026-10-26 13 d ago also GHSA-vrg7-482j-p6f6 , PYSEC-2026-2503 , EUVD-2026-29855
- cvss
- 7.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 33%
- public exploits
- 0
- none known
Summary
Granian is a Rust HTTP server for Python applications. From 1.2.0 to 2.7.4, Granian aborts a worker process when an unauthenticated client sends a WebSocket upgrade request whose Sec-WebSocket-Protocol header contains non-ASCII bytes. The crash happens in Granian's WebSocket scope construction path, before the ASGI application is invoked. This vulnerability is fixed in 2.7.4.
Patch / fix
- pypi granian 2.7.4
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 5 mo ago
Exploit prediction
0.39% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/emmett-framework/granian/security/advisories/GHSA-vrg7-482j-p6f6 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| GitHub | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| OSV | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | granian | >=1.2.0, <2.7.4 |
2.7.4 |
Affected products
- emmett-framework granian
Classification
References
Sources
- CVE List CVE-2026-42544
- GitHub Advisory GHSA-vrg7-482j-p6f6
- NVD CVE-2026-42544
- OSV PYSEC-2026-2503
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