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CVE-2025-23167VulnerabilityPublished Updated

Microsoft · 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

Affects MicrosoftSource GCVE Database

0

Not known to be exploited.

Data as of 25 Oct 2026, 19:02 UTC

Severity
High

Rated by Threat Radar · No CVSS score from NVD or the CNA

EPSS
0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 2 May 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

What to do

Affected software

ProductAffectedFixed in
Debianazure-linuxpkg:deb/azure-linuxOther threatsAffected
  • =2.0
  • =3.0
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until an official fix is available, organizations should review their proxy and HTTP handling configurations to detect and mitigate potential request smuggling attempts. No vendor advisory or patch links are currently provided, so monitoring official Microsoft channels for updates is recommended.

Description

CVE-2025-23167 is a vulnerability in Node.js 20's HTTP parser where HTTP/1 headers can be improperly terminated using '\r\n\rX' instead of the required '\r\n\r\n'. This inconsistency enables HTTP request smuggling, potentially allowing attackers to bypass proxy-based access controls and submit unauthorized requests. The vulnerability affects certain Microsoft products including Azure Linux versions 2.0 and 3.0. No CVSS score or patch information is currently available, and there are no known exploits in the wild at this time.

References

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