CVE-2021-3700 Use after free in usbredir

What is CVE-2021-3700?

CVE-2021-3700 is a medium-severity use after free vulnerability in Debian Debian Linux, published on 24 Feb 2022. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A use-after-free vulnerability was found in usbredir in versions prior to 0.11.0 in the usbredirparser_serialize() in usbredirparser/usbredirparser.c. This issue occurs when serializing large amounts of buffered write data in the case of a slow or blocked destination.

Weakness: CWE-416

Which versions are affected by CVE-2021-3700?

It affects 4 products.

Products include Debian Debian Linux, Fedoraproject Fedora, Redhat Enterprise Linux, Spice-Space Usbredir.

How do I fix CVE-2021-3700?

Upgrade to a fixed version.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2021-3700 being exploited?

There is no known exploitation of CVE-2021-3700 in the wild and no public exploit code.

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• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-8824, DEBIAN-CVE-2021-3700, DLA-2958-1, GHSA-9885-wxqj-48q7, MGASA-2022-0133, OESA-2021-1355 and 3 more.