CVE-2026-23531

CVE-2026-23531 is a critical-severity vulnerability in Freerdp with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-122.

Key facts

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0, in ClearCodec, when `glyphData` is present, `clear_decompress` calls `freerdp_image_copy_no_overlap` without validating the destination rectangle, allowing an out-of-bounds read/write via crafted RDPGFX surface updates. 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.

Frequently asked questions

What is CVE-2026-23531?
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0, in ClearCodec, when `glyphData` is present, `clear_decompress` calls `freerdp_image_copy_no_overlap` without validating the destination rectangle, allowing an out-of-bounds read/write via crafted RDPGFX surface updates. 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.
How severe is CVE-2026-23531?
CVE-2026-23531 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-23531 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-23531?
CVE-2026-23531 affects Freerdp. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-23531?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-23531 have an EU (EUVD) identifier?
Yes. CVE-2026-23531 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-3317.
When was CVE-2026-23531 published?
CVE-2026-23531 was published on 2026-01-19 and last updated on 2026-06-30.

References

Affected products (1)

More vulnerabilities in Freerdp

All CVEs affecting Freerdp →

Other CWE-122 (Heap-based Buffer Overflow) vulnerabilities

Browse all CWE-122 (Heap-based Buffer Overflow) vulnerabilities →