Granian: Unauthenticated DoS via WebSocket subprotocol header panic
Priority HIGH 72CWE-20Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-248.
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.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.0039 33rd percentileScored 2026-11-07
Fix Fixed granian (emmett-framework): 2.7.4granian (PyPI): 2.7.4
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| emmett-framework | granian | 1.2.0 to before 2.7.4 | 2.7.4 | Patch available | CNA |
| — | granian (PyPI) | 1.2.0 to before 2.7.4 | 2.7.4 | Patch available | GHSA-vrg7-482j-p6f6 |
- granian Vendoremmett-framework Affected 1.2.0 to before 2.7.4 Fixed in 2.7.4 Patch available CNA
- granian (PyPI) Vendor— Affected 1.2.0 to before 2.7.4 Fixed in 2.7.4 Patch available GHSA-vrg7-482j-p6f6
Remediation
- Fix · CNA granian (emmett-framework) Fixed in 2.7.4
- Fix · GHSA-vrg7-482j-p6f6 granian (PyPI) Fixed in 2.7.4 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-42544
- 2026-10-03 Alias added: GHSA-vrg7-482j-p6f6
References
More emmett-framework vulnerabilities
- TI-2026-20684 Emmett has an Unhandled CookieError Exception Causing Denial of Service CVSS 3.1HIGH 7.5
- TI-2026-30825 Granian: DoS via WSGI response header panic CVSS 3.1MEDIUM 5.9
Sources
- CVE-2026-42544 · CVE Program
- CVE-2026-42544 · NVD
- FIRST EPSS
- GHSA-vrg7-482j-p6f6 · GitHub Advisory Database · CC BY 4.0
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