CVE-2026-23732: FreeRDP has heap-buffer-overflow in Glyph_Alloc

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-01-19 · updated 2026-06-17
Weakness: CWE-122

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0, FastGlyph parsing trusts `cbData`/remaining length and never validates against the minimum size implied by `cx/cy`. A malicious server can trigger a client‑side global buffer overflow, causing a crash (DoS). Version 3.21.0 contains a patch for the issue.

Affected products

FreeRDP: before 3.21.0 — fixed in 3.21.0

How to fix

Upgrade to a fixed version: FreeRDP 3.21.0. Check the vendor advisory for mitigations.

References

https://github.com/FreeRDP/FreeRDP/blob/f96ee2a6dd02739325c2a4e36a14978b561f00ea/libfreerdp/cache/glyph.c#L463-L480
https://github.com/FreeRDP/FreeRDP/blob/f96ee2a6dd02739325c2a4e36a14978b561f00ea/libfreerdp/codec/color.c#L261-L277
https://github.com/FreeRDP/FreeRDP/blob/f96ee2a6dd02739325c2a4e36a14978b561f00ea/libfreerdp/core/graphics.c#L138
https://github.com/FreeRDP/FreeRDP/blob/f96ee2a6dd02739325c2a4e36a14978b561f00ea/libfreerdp/core/orders.c#L2186C17-L2199
https://github.com/FreeRDP/FreeRDP/releases/tag/3.21.0
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-7qxp-j2fj-c3pp
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-7qxp-j2fj-c3pp

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