CVE-2026-33986: FreeRDP: H.264 YUV Buffer Dimension Desync - Heap OOB Write

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: none known
Published: 2026-03-30 · updated 2026-07-15
Weakness: CWE-122

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.24.2, in yuv_ensure_buffer() in libfreerdp/codec/h264.c, h264->width and h264->height are updated before the reallocation loop. If any winpr_aligned_recalloc() call fails, the function returns FALSE but width/height are already inflated. This issue has been patched in version 3.24.2.

Affected products

FreeRDP: before 3.24.2 — fixed in 3.24.2

How to fix

Upgrade to a fixed version: FreeRDP 3.24.2. Check the vendor advisory for mitigations.

References

https://github.com/FreeRDP/FreeRDP/commit/f6e43e208958140074ae9bb93cd0c9045a371c77
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-h6qw-wxvm-hf97
https://access.redhat.com/security/cve/CVE-2026-33986
https://bugzilla.redhat.com/show_bug.cgi?id=2453221
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33986.json

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