CVE-2026-91954: FreeRDP before 3.31.0 NULL Pointer Dereference via NSCodec

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-09-15 · updated 2026-09-24
Weakness: CWE-476

Description

FreeRDP before 3.31.0 contains a null pointer dereference vulnerability in gdi_surface_bits when processing Surface Bits commands with NSCodec codec ID. A malicious RDP server can crash a FreeRDP client by sending a crafted Surface Bits command claiming to use NSCodec, even when the codec is disabled.

Affected products

FreeRDP: before 3.31.0 — fixed in 3.31.0

How to fix

Upgrade to a fixed version: FreeRDP 3.31.0. Check the vendor advisory for mitigations.

References

https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-ffjr-p229-hpch
https://www.vulncheck.com/advisories/freerdp-before-3.31.0-null-pointer-dereference-via-nscodec

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