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Microsoft Security Response CenterCVE-2025-27219

In the CGI gem before 0.4.2 for Ruby, the CGI::Cookie.parse method in the CGI library contains a potential Denial of Service (DoS) vulnerability. The method does not impose any limit on the length of the raw cookie value it processes. This oversight can lead to excessive resource consumption when parsing extremely large cookies.

Is Azure Linux the only Microsoft product that includes this open-source library and is therefore potentially affected by this vulnerability? One of the main benefits to our customers who choose to use the Azure Linux distro is the commitment to keep it up to date with the most recent and most secure versions of the open source libraries with which the distro is composed. Microsoft is committed to transparency in this work which is why we began publishing CSAF/VEX in October 2025. See this blog post for more information. If impact to additional products is identified, we will update the CVE to reflect this.

Read the vendor bulletin Get alerts for cbl2 ruby 3.1.4-9 on CBL Mariner
5.3CVSS out of 10Medium severity
Scope

What the vendor says is affected

  • cbl2 ruby 3.1.4-9 on CBL Mariner 2.0
  • azl3 ruby 3.3.5-3 on Azure Linux 3.0
  • cbl2 ruby 3.1.4-9 on CBL-Mariner 2.0

Versions the vendor lists as fixed

  • 3.1.4-9
  • 3.3.5-3
Next step

What the vendor recommends

CBL-Mariner Releases

Review the complete instructions on the vendor's site
Timeline

When this advisory changed

  1. Published by Microsoft Security Response Center

    The publication date reported by the vendor.

  2. Updated by Microsoft Security Response Center

    The vendor changed the advisory after it was first published.

  3. Added to SecurityAlert

    We collected the advisory from the official source.

Vulnerabilities

CVEs named in this advisory

CVE-2025-27219View CVSS, KEV, EPSS, and threat context
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