What’s Vulnerable › Vulnerabilities

CVE-2026-44421: FreeRDP RDPGFX CacheToSurface heap-buffer-overflow via clamped-rectangle validation bypass

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-05-29 · updated 2026-07-27
• Weakness: CWE-122

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.26.0, a malicious RDP server can trigger a heap-buffer-overflow write in the FreeRDP client by sending crafted RDPGFX PDUs. The bug is in gdi_CacheToSurface: it validates a destination rectangle that is clamped to UINT16_MAX, but then performs the copy using the original cacheEntry->width/height. This can cause a large out-of-bounds heap write and may lead to client crashes or code execution. This bug is reachable from a malicious RDP server, but only when the client has RDPGFX enabled. This vulnerability is fixed in 3.26.0.

Affected products

• FreeRDP: before 3.26.0 — fixed in 3.26.0

How to fix

Upgrade to a fixed version: FreeRDP 3.26.0. Check the vendor advisory for mitigations.

References

• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-p6r2-4hgm-m6ff
• https://access.redhat.com/errata/RHSA-2026:36203
• https://access.redhat.com/errata/RHSA-2026:46393
• https://access.redhat.com/security/cve/CVE-2026-44421
• https://bugzilla.redhat.com/show_bug.cgi?id=2483471
• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-p6r2-4hgm-m6ff
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44421.json

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