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Microsoft Security Response CenterCVE-2025-40909

Perl threads have a working directory race condition where file operations may target unintended paths

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 cm2 perl 5.34.1-491 on CBL Mariner
5.9CVSS out of 10Medium severity
Scope

What the vendor says is affected

  • cm2 perl 5.34.1-491 on CBL Mariner 2.0
  • cbl2 perl 5.34.1-491 on CBL Mariner 2.0
  • azl3 perl 5.38.2-509 on Azure Linux 3.0
  • cbl2 perl 5.34.1-491 on CBL-Mariner 2.0

Versions the vendor lists as fixed

  • 5.34.1-491
  • 5.38.2-509
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-2025-40909View CVSS, KEV, EPSS, and threat context
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