What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-03-13 · updated 2026-06-17
• Weakness: CWE-369

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.

Affected products

• FreeRDP: before 3.24.0 — fixed in 3.24.0

How to fix

Upgrade to a fixed version: FreeRDP 3.24.0. Check the vendor advisory for mitigations.

References

• https://github.com/FreeRDP/FreeRDP/commit/03b48b3601d867afccac1cdc6081de7a275edce7
• https://github.com/FreeRDP/FreeRDP/commit/16df2300e1e3f5a51f68fb1626429e58b531b7c8
• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-jp7m-94ww-p56r
• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-jp7m-94ww-p56r

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