MEDIUM 6.5 Microsoft
CVE-2025-23167
A flaw in Node.js 20's HTTP parser allows improper termination of HTTP/1 headers using `\r\n\rX` instead of the required `\r\n\r\n`. This inconsistency enables request smuggling, allowing attackers to bypass proxy-based access controls and submit unauthorized requests. The issue was resolved by upgrading `llhttp` to version 9, which enforces correct header termination. Impact: * This vulnerability affects only Node.js 20.x users prior to the `llhttp` v9 upgrade.
Microsoft Security Update 2025-May: A flaw in Node.js 20's HTTP parser allows improper termination of HTTP/1 headers using `\r\n\rX` instead of the required `\r\n\r\n`.
This inconsistency enables request smuggling, allowing attackers to bypass proxy-based access controls and submit unauthorized requests.
The issue was resolved by upgrading `llhttp` to version 9, which enforces correct header termination.
Impact:
* This vulnerability affects only Node.js 20.x users prior to the `llhttp` v9 upgrade.
Affected Products
- azl3 nodejs 20.14.0-9 on Azure Linux 3.0
- azl3 fluent-bit 3.1.9-4 on Azure Linux 3.0
- cbl2 fluent-bit 3.0.6-2 on CBL Mariner 2.0
- cbl2 nghttp2 1.57.0-2 on CBL Mariner 2.0
- cbl2 nodejs18 18.20.3-8 on CBL Mariner 2.0
- azl3 nodejs 20.14.0-10 on Azure Linux 3.0
- azl3 nodejs 20.14.0-14 on Azure Linux 3.0
- cbl2 nodejs18 18.20.3-12 on CBL Mariner 2.0
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-23167
- https://nvd.nist.gov/vuln/detail/CVE-2025-23167
This medium severity vulnerability with a CVSS score of 6.5 was published on 2025-05-13 via Microsoft. Affected: azl3 nodejs 20.14.0-9 on Azure Linux 3.0, azl3 fluent-bit 3.1.9-4 on Azure Linux 3.0, cbl2 fluent-bit 3.0.6-2 on CBL Mariner 2.0 and 5 more.
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