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CVE-2026-42544— Granian: Unauthenticated DoS via WebSocket subprotocol header panic

Quick assessment

Affected
emmett-framework granian
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

granian是Emmett开源的一款基于Rust的高性能Python HTTP服务器。 granian 1.2.0版本至2.7.4版本存在输入验证错误漏洞，该漏洞源于未经验证的客户端发送包含非ASCII字节的Sec-WebSocket-Protocol标头的WebSocket升级请求时，Granian中止工作进程。

CVSS 7.5 · High EPSS 0.46% · P38

Affected Version Matrix 1

VendorProduct Version RangeStatus
emmett-framework granian >= 1.2.0, < 2.7.4 affected
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I. Basic Information for CVE-2026-42544

Vulnerability Information
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Vulnerability Title
Granian: Unauthenticated DoS via WebSocket subprotocol header panic
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
输入验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
granian 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
granian是Emmett开源的一款基于Rust的高性能Python HTTP服务器。 granian 1.2.0版本至2.7.4版本存在输入验证错误漏洞，该漏洞源于未经验证的客户端发送包含非ASCII字节的Sec-WebSocket-Protocol标头的WebSocket升级请求时，Granian中止工作进程。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
emmett-framework granian >= 1.2.0, < 2.7.4 -

II. Public POCs for CVE-2026-42544

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III. Intelligence Information for CVE-2026-42544

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Vendor Advisories for CVE-2026-42544 (1)

IV. Related Vulnerabilities

Same product: granian
Same vendor: emmett-framework
Same weakness: CWE-20

V. Comments for CVE-2026-42544

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