FreeRDP RDPGFX CacheToSurface heap-buffer-overflow via clamped-rectangle validation bypass

Summary

CVE	CVE-2026-44421
State	PUBLISHED
Assigner	GitHub_M
Source Priority	CVE Program / NVD first with legacy fallback
Published	2026-05-29 20:16:24 UTC
Updated	2026-07-08 13:16:45 UTC
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.

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from ADP

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

EPSS: 0.004200000 probability, percentile 0.338540000 (date 2026-07-09)

Problem Types: CWE-122 | CWE-787 | CWE-122 CWE-122: Heap-based Buffer Overflow | CWE-787 Out-of-bounds Write

Version	Source	Type	Score	Severity	Vector
3.1	ADP	CVSS	8.8	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`
3.1	[email protected]	Secondary	8.8	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`
3.1	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	Secondary	8.8	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`
3.1	CNA	DECLARED	8.8	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`

CVSS v3.1 Breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

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

NVD Known Affected Configurations (CPE 2.3)

Type	Vendor	Product	Version	Update	Edition	Language
Application	Freerdp	Freerdp	All	All	All	All

Vendor Declared Affected Products

Source	Vendor	Product	Version	Platforms
CNA	FreeRDP	FreeRDP	affected < 3.26.0	Not specified
ADP	Red Hat	Red Hat Enterprise Linux AppStream V. 10	Not specified	Not specified
ADP	Red Hat	Red Hat Enterprise Linux CodeReady Linux Builder V. 10	Not specified	Not specified
ADP	Red Hat	Red Hat Enterprise Linux 6	Not specified	Not specified
ADP	Red Hat	Red Hat Enterprise Linux 7	Not specified	Not specified
ADP	Red Hat	Red Hat Enterprise Linux 8	Not specified	Not specified
ADP	Red Hat	Red Hat Enterprise Linux 9	Not specified	Not specified

References

Reference	Source	Link	Tags
github.com/FreeRDP/FreeRDP/security/advisories/GHSA-p6r2-4hgm-m6ff	134c704f-9b21-4f2e-91b3-4a467353bcc0	github.com	Exploit, Mitigation, Vendor Advisory
access.redhat.com/security/cve/CVE-2026-44421	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	access.redhat.com
bugzilla.redhat.com/show_bug.cgi	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	bugzilla.redhat.com
access.redhat.com/errata/RHSA-2026:36203	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	access.redhat.com
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44421.json	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	security.access.redhat.com
CVE Program record	CVE.ORG	www.cve.org	canonical
NVD vulnerability detail	NVD	nvd.nist.gov	canonical, analysis

No vendor comments have been submitted for this CVE.

Additional Advisory Data

Source	Time	Event
ADP	2026-05-29T21:01:24.644Z	Reported to Red Hat.
ADP	2026-05-29T19:40:25.492Z	Made public.

Solutions

ADP: RHSA-2026:36203: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)

Workarounds

ADP: To mitigate this vulnerability, disable the RDPGFX graphics acceleration feature in your FreeRDP client configuration. Additionally, avoid using FreeRDP to connect to untrusted or unknown external servers. This may cause a temporary disruption in service for your users.

There are currently no legacy QID mappings associated with this CVE.