Buffer overflow in Freerdp
CVE-2026-29774
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, a client-side heap buffer overflow occurs in the FreeRDP client's AVC420/AVC444 YUV-to-RGB conversion path due to missing horizontal bounds validation of H.264 metablock regionRects coordinates. In yuv.c, the clamp() function (line 347) only validates top/bottom against the surface/YUV height, but never checks left/right against the surface width. When avc420_yuv_to_rgb (line 67) computes destination and source pointers using rect->left, it performs unchecked pointer arithmetic that can reach far beyond the allocated surface buffer. A malicious server sends a WIRE_TO_SURFACE_PDU_1 with AVC420 codec containing a regionRects entry where left greatly exceeds the surface width (e.g., left=60000 on a 128px surface). The H.264 bitstream decodes successfully, then yuv420_process_work_callback calls avc420_yuv_to_rgb which computes pDstPoint = pDstData + rect->top * nDstStep + rect->left * 4, writing 16-byte SSE vectors 1888+ bytes past the allocated heap region. This vulnerability is fixed in 3.24.0.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.005 (39.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 39.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
- Freerdp — versions < 3.24.0
Weakness classification (CWE)
References
- github.com/FreeRDP/FreeRDP/security/advisories/GHSA-5q35-hv9x-7794 (Exploit, Patch, Vendor Advisory)
- github.com/FreeRDP/FreeRDP/commit/6482b7a92fff3959582cef052d1967ad6bde3738 (Patch)
Frequently asked questions
- What is CVE-2026-29774?
- CVE-2026-29774 is a medium-severity vulnerability in Freerdp, classified under Out-of-bounds Write. CVSS score: 5.3/10. Published 2026-03-13.
- How severe is CVE-2026-29774?
- Medium severity. CVSS v3 base score is 5.3 out of 10.