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Description

FreeRDP before 3.26.0 contains a heap-buffer-overflow vulnerability in gdi_CacheToSurface that allows remote attackers to write out-of-bounds heap memory. The vulnerability occurs because rectangle validation clamps coordinates to UINT16_MAX but performs copy operations using unclamped cache entry dimensions, enabling malicious RDP servers to trigger large out-of-bounds writes and potentially achieve remote code execution or client crash.

PUBLISHED Reserved 2026-04-08 | Published 2026-05-26 | Updated 2026-05-27 | Assigner VulnCheck




HIGH: 8.6CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
HIGH: 8.8CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Problem types

Heap-based Buffer Overflow

Product status

Default status
unaffected

Any version before 3.26.0
affected

3.26.0 (semver)
unaffected

Credits

kevin-valerio reporter

References

github.com/...reeRDP/security/advisories/GHSA-p6r2-4hgm-m6ff exploit

github.com/...reeRDP/security/advisories/GHSA-p6r2-4hgm-m6ff (GHSA Advisory GHSA-p6r2-4hgm-m6ff) vendor-advisory

github.com/...ommit/23b36cd00ebf0ccd97750fcdbc9aa2f362352da7 patch

www.vulncheck.com/...surface-via-rectangle-validation-bypass (VulnCheck Advisory: FreeRDP - Heap-buffer-overflow in gdi_CacheToSurface via rectangle validation bypass) third-party-advisory

cve.org (CVE-2026-40033)

nvd.nist.gov (CVE-2026-40033)

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