dbcve.org
Improper Input ValidationWeakness · CWE-20

CVE-2026-42544

HIGH · 7.5 CVSS v3.1 Published 2026-05-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Granian HTTP server crashes worker processes when handling unauthenticated WebSocket upgrade requests containing non-ASCII bytes in the Sec-WebSocket-Protocol header. The crash occurs during WebSocket scope construction, before the ASGI application is invoked, resulting in denial of service.

MitigationUpgrade Granian to version 2.7.4 or later to resolve the worker process crash vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm Granian is installed
    Run `pip show granian` or `pip list | grep granian` to check if the Granian package is present in the environment
    Affected if Granian package is not installed, the system is not affected by this specific vulnerability
  2. Identify installed Granian version
    Check the version field from the `pip show granian` output and compare it to the affected range (versions prior to 2.7.4)
    Affected if The installed version is 2.7.3 or earlier, placing it within the vulnerable version range
  3. Determine if WebSocket support is enabled
    Inspect the Granian server configuration or startup command for WebSocket protocol handling. Look for ASGI app configurations that include websocket=True or similar WebSocket-enabled route definitions
    Affected if WebSocket handling is enabled and exposed to unauthenticated clients; the crash occurs specifically during WebSocket upgrade request processing
  4. Check network exposure of the Granian server
    Review firewall rules, network bindings, and server startup parameters to confirm whether the Granian HTTP server is accessible to unauthenticated remote clients
    Affected if The server is network-accessible to unauthenticated users, making it possible to trigger the malicious WebSocket upgrade request

The environment is affected if Granian version is 2.7.3 or earlier AND the server has WebSocket support enabled and is accessible to unauthenticated clients, allowing them to send malformed WebSocket upgrade requests with non-ASCII bytes in the Sec-WebSocket-Protocol header.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Granian to version 2.7.4 or later to resolve the worker process crash vulnerability.

Recommended fix High confidence

Upgrade to Granian version 2.7.4 or later

  1. 1. Identify the current Granian version in use by checking your project's dependencies (e.g., pyproject.toml, requirements.txt) or running `pip show granian`
  2. 2. If running a version between 1.2.0 and 2.7.3 inclusive, plan for upgrade to version 2.7.4 or later
  3. 3. Update the Granian dependency in your project configuration to specify version 2.7.4 or higher (e.g., `graniain>=2.7.4`)
  4. 4. Run dependency update/install (e.g., `pip install -U granian` or `pip install granian>=2.7.4`)
  5. 5. Restart all Granian worker processes to load the updated version
  6. 6. Verify the upgrade was successful by checking the installed version
Caveat Review release notes between your current version and 2.7.4 for any breaking changes in behavior or API

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-42544 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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