CVE-2026-42544

Granian: Unauthenticated DoS via WebSocket subprotocol header panic

HIGH
7.5
CVSS Score
Published: May 12, 2026 at 09:46 PM UTC
Updated: October 26, 2026 at 02:10 PM UTC
1 product affected across 1 vendorGranian

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Severity
HIGH7.5
Exploit prediction
EPSS 0.4%
SSVC
PoC

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

1.2.0 ≤ v < 2.7.41.2.0
Affected range stops below 2.7.4, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-20CWE-248CWE-400

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