CVE-2026-31884 FreeRDP has a division-by-zero in ADPCM decoders when `nBlockAlign` is 0

Medium 6.5 Published 13 Mar 2026 Updated 16 Mar 2026

A division-by-zero error in FreeRDP ADPCM decoders allows remote attackers to cause a crash via a malformed PDU.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2026-31884?

CVE-2026-31884 is a medium-severity denial of service vulnerability in Freerdp Freerdp, published on 13 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, division by zero in MS-ADPCM and IMA-ADPCM decoders when nBlockAlign is 0, leading to a crash. In libfreerdp/codec/dsp.c, both ADPCM decoders use size % block_size where block_size = context->common.format.nBlockAlign. The nBlockAlign value comes from the Server Audio Formats PDU on the RDPSND channel. The value 0 is not validated anywhere before reaching the decoder. When nBlockAlign = 0, the modulo operation causes a SIGFPE (floating point exception) crash. This vulnerability is fixed in 3.24.0.

Weakness: CWE-369

Which versions are affected by CVE-2026-31884?

It affects 1 product.

Products include Freerdp Freerdp.

How do I fix CVE-2026-31884?

Upgrade to a fixed version.

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-2026-31884 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-31884 exists.

All Freerdp Freerdp vulnerabilities

Sources

Also known as DEBIAN-CVE-2026-31884, GHSA-jp7m-94ww-p56r, UBUNTU-CVE-2026-31884.