CVE-2026-29776: Integer Underflow in FreeRDP

The integer underflow vulnerability resides within the updatereadcachebitmaporder function of the FreeRDP Core Library. An attacker could exploit this by crafting malicious Remote Desktop Protocol (RDP) traffic, specifically targeting bitmap handling. Successful exploitation could cause FreeRDP to crash or become unresponsive, resulting in a denial-of-service. While the CVSS score is LOW, a denial-of-service can disrupt remote access and potentially impact critical services relying on RDP connectivity. The impact is primarily focused on the FreeRDP client or server process, with limited potential for broader system compromise.

1. Reserved2026-03-04
2. Published2026-03-13
3. Modified2026-03-16
4. EPSS updated2026-03-23

The primary mitigation for CVE-2026-29776 is to upgrade FreeRDP to version 3.24.0 or later. If immediate upgrading is not feasible, consider implementing temporary workarounds such as restricting RDP access to trusted networks or employing network segmentation to limit the blast radius of a potential attack. While a WAF or proxy might not directly prevent this integer underflow, it can help mitigate the impact by rate-limiting RDP connections and filtering potentially malicious traffic patterns. After upgrading, confirm the fix by attempting to connect to the FreeRDP server with a standard RDP client and verifying that no crashes or unexpected behavior occurs.