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CVE-2026-40033

8.8 · HIGH

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.

Published May 26, 2026CWE-122EPSS 1.06%

Overview

CVE-2026-40033 is a high-severity vulnerability. It was published on May 26, 2026 and has a CVSS 3.1 base score of 8.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.8, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/FreeRDP/FreeRDP/commit/d7508ebcd82842a691ae4941e5104d14240a89aeGitHubgithub.com/FreeRDP/FreeRDP/pull/12713GitHubgithub.com/FreeRDP/FreeRDP/security/advisories/GHSA-p6r2-4hgm-m6ffRefwww.vulncheck.com/advisories/freerdp-heap-buffer-overflow-in-gdi-cachetosurface-via-rectangle-validation-bypassRefaccess.redhat.com/errata/RHSA-2026:36203Refaccess.redhat.com/errata/RHSA-2026:46393Refaccess.redhat.com/security/cve/CVE-2026-40033Refbugzilla.redhat.com/show_bug.cgi?id=2481473GitHubgithub.com/FreeRDP/FreeRDP/security/advisories/GHSA-p6r2-4hgm-m6ffRefsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40033.json

How CyberStrike helps

Frequently asked questions

What is CVE-2026-40033?

CVE-2026-40033 is a high-severity vulnerability. It was published on May 26, 2026 and has a CVSS 3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-40033?

This vulnerability has a CVSS 3.1 base score of 8.8, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-40033?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-40033?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-40033 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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