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FreeRDP CVE-2026-23534

HIGH
Heap-based Buffer Overflow (CWE-122)
2026-01-19 security-advisories@github.com
Buffer Overflow Freerdp Heap Overflow
7.7
CVSS 4.0 · Vendor: github
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Severity by source

Vendor (github) PRIMARY
7.7 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
6.5 MEDIUM

Malicious server attacks a connecting client, so UI:R for the user-initiated connection; confirmed impact is a client crash (A:H) with no proven C/I impact.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat
7.6 HIGH
qualitative

Primary rating from Vendor (github).

CVSS VectorVendor: github

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

11
Analysis Updated
Jun 30, 2026 - 06:03 vuln.today
v5 (cvss_changed)
Analysis Updated
Jun 30, 2026 - 06:03 vuln.today
v4 (cvss_changed)
Analysis Updated
Jun 30, 2026 - 06:03 vuln.today
v3 (cvss_changed)
Analysis Updated
Jun 30, 2026 - 06:03 vuln.today
v2 (cvss_changed)
Re-analysis Queued
Jun 30, 2026 - 03:23 vuln.today
cvss_changed
Severity Changed
Jun 30, 2026 - 03:23 NVD
CRITICAL HIGH
CVSS changed
Jun 30, 2026 - 03:23 NVD
9.8 (CRITICAL) 7.7 (HIGH)
Patch released
Apr 09, 2026 - 20:30 nvd
Patch available
Analysis Generated
Mar 12, 2026 - 21:54 vuln.today
PoC Detected
Jan 28, 2026 - 18:44 vuln.today
Public exploit code
CVE Published
Jan 19, 2026 - 18:16 nvd
CRITICAL 9.8

DescriptionCVE.org

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0, a client-side heap buffer overflow occurs in the ClearCodec bands decode path when crafted band coordinates allow writes past the end of the destination surface buffer. A malicious server can trigger a client‑side heap buffer overflow, causing a crash (DoS) and potential heap corruption with code‑execution risk depending on allocator behavior and surrounding heap layout. Version 3.21.0 contains a patch for the issue.

AnalysisAI

Denial of service (and potential code execution) in FreeRDP RDP clients before 3.21.0 lets a malicious or compromised RDP server overflow a client-side heap buffer during ClearCodec band decoding. By supplying crafted band coordinates that drive writes past the destination surface buffer, the server crashes the connecting client and may corrupt the heap. Publicly available exploit code exists; EPSS is low (0.15%, 35th percentile) and the issue is not in CISA KEV, indicating no confirmed active exploitation.

Technical ContextAI

FreeRDP is the dominant open-source implementation of the Remote Desktop Protocol used by clients such as Remmina, GNOME Connections, Weston, and embedded RDP front-ends, and is redistributed by Red Hat and SUSE (hence the multiple distro errata). The flaw is a CWE-122 heap-based buffer overflow in the ClearCodec decoder (libfreerdp/codec/clear.c, around lines 878-884), a bitmap compression codec negotiated during an RDP session. When decoding the 'bands' portion of a ClearCodec stream, attacker-controlled band coordinates are not validated against the destination surface dimensions, so pixel writes can extend beyond the allocated surface buffer. The CPE cpe:2.3:a:freerdp:freerdp confirms the affected component is the FreeRDP library itself rather than any single downstream product.

RemediationAI

Vendor-released patch: upgrade FreeRDP to version 3.21.0 or later (https://github.com/FreeRDP/FreeRDP/releases/tag/3.21.0). On enterprise Linux, apply the corresponding distribution package updates instead of building from source - Red Hat customers via RHSA-2026:2222/2952/2081/2048/2736/3037 and SUSE customers via SUSE-SU-2026:0345/0417/0421/0449/0559 - and restart any long-running RDP client sessions or services that link the FreeRDP library so the patched code is loaded. If immediate patching is not possible, the most effective compensating control is to restrict outbound RDP client connections to known, trusted servers only (the attack requires the client to connect to a malicious server), for example via firewall egress rules or connection allow-lists; the trade-off is reduced flexibility for ad-hoc remote connections. Where feasible, also disable or avoid ClearCodec/codec negotiation on client connections to untrusted hosts, accepting degraded bitmap compression performance. Review GHSA-3frr-mp8w-4599 for codec-specific guidance.

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Same weakness CWE-122 – Heap-based Buffer Overflow

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Vendor StatusVendor

SUSE

Severity: Critical
Product Status
Container suse/sl-micro/6.0/baremetal-os-container:latest Container suse/sl-micro/6.0/kvm-os-container:latest Container suse/sl-micro/6.0/rt-os-container:latest Affected
Container suse/sl-micro/6.0/base-os-container:latest Container suse/sl-micro/6.0/toolbox:latest Image SL-Micro Image SLE-Micro Image SLE-Micro-Azure Image SLE-Micro-BYOS Image SLE-Micro-BYOS-Azure Image SLE-Micro-BYOS-EC2 Image SLE-Micro-BYOS-GCE Image SLE-Micro-EC2 Image SLE-Micro-GCE Affected
Container suse/sl-micro/6.1/baremetal-os-container:2.2.1-7.43 Container suse/sl-micro/6.1/kvm-os-container:2.2.1-5.67 Container suse/sl-micro/6.1/rt-os-container:2.2.1-5.57 Affected
Container suse/sl-micro/6.1/base-os-container:2.2.1-5.64 Image SL-Micro-Azure Image SL-Micro-BYOS-Azure Image SL-Micro-BYOS-EC2 Image SL-Micro-BYOS-GCE Image SL-Micro-EC2 Image SUSE-Multi-Linux-Manager-Proxy-BYOS-Azure Image SUSE-Multi-Linux-Manager-Proxy-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Proxy-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-Azure-llc Image SUSE-Multi-Linux-Manager-Server-Azure-ltd Image SUSE-Multi-Linux-Manager-Server-BYOS-Azure Image SUSE-Multi-Linux-Manager-Server-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Server-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-EC2-llc Image SUSE-Multi-Linux-Manager-Server-EC2-ltd Affected
SUSE Liberty Linux 8 Fixed

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CVE-2026-23534 vulnerability details – vuln.today
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