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Vulnerability record · CVE-2026-44421 · published 29 May 2026

CVE-2026-44421: Freerdp heap-based buffer overflow vulnerability

Freerdp · Freerdp

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.

8.8 CVSS 3.1 High EPSS 0.72% · top 48.1% CWE-122 · Heap-based buffer overflowCWE-787 · Out-of-bounds write
8.8CVSS 3.1 base score
0.72%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
7References, 2 tagged exploit
27 Jul 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-p6r2-4hgm-m6ff ExploitMitigationVendor Advisory
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 ExploitMitigationVendor Advisory
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44421.json

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-44421), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.