CVE-2021-3527 Denial of service in QEMU

What is CVE-2021-3527?

CVE-2021-3527 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 26 May 2021. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A flaw was found in the USB redirector device (usb-redir) of QEMU. Small USB packets are combined into a single, large transfer request, to reduce the overhead and improve performance. The combined size of the bulk transfer is used to dynamically allocate a variable length array (VLA) on the stack without proper validation. Since the total size is not bounded, a malicious guest could use this flaw to influence the array length and cause the QEMU process to perform an excessive allocation on the stack, resulting in a denial of service.

Weakness: CWE-770

Which versions are affected by CVE-2021-3527?

It affects 3 products.

Products include Debian Debian Linux, Qemu Qemu, Redhat Enterprise Linux.

How do I fix CVE-2021-3527?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2021-3527 being exploited?

There is no known exploitation of CVE-2021-3527 in the wild and no public exploit code.

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All Debian Debian Linux vulnerabilities

Sources

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

Also known as DEBIAN-CVE-2021-3527, GHSA-fwv2-775h-qv4v, UBUNTU-CVE-2021-3527.