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Microsoft Security Response CenterCVE-2018-21035

In Qt through 5.14.1 the WebSocket implementation accepts up to 2GB for frames and 2GB for messages. Smaller limits cannot be configured. This makes it easier for attackers to cause a denial of service (memory consumption).

HighVendor CVSS 7.5 / 10 1 CVE Published Oct 1, 2021 at 12:00 AM UTC

Summary

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.

Products covered

  • cm1 qt5-qtsvg 5.12.11-2 on CBL Mariner 1.0

  • cbl2 qt5-qtsvg 5.12.11-3 on CBL Mariner 2.0

Remediation

CBL-Mariner Releases

Vendor-listed fixes

  • 5.12.11-2

  • 5.12.11-3

CVEs in this advisory 1

Updates

  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.