What’s Vulnerable › Vulnerabilities

CVE-2026-55194: FreeRDPHeap-buffer-overflow write in TS Gateway RPC RESPONSE reassembly due to alloc_hint capacity mismatch

• Severity: critical (CVSS 9.8 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: 2026-08-19 · updated 2026-10-26
• Weakness: CWE-122

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, rpc_client_recv_fragment in libfreerdp/core/gateway/rpc_client.c ensures the response reassembly stream capacity using only the server-declared alloc_hint rather than the actual StubLength about to be written. A malicious TS Gateway can send a PTYPE_RESPONSE with a small alloc_hint and a much larger frag_length, causing Stream_Write to copy attacker-controlled stub data beyond the 4096-byte pdu->s buffer. This can crash the client and may permit code execution through heap corruption. This issue is fixed in version 3.27.0.

Affected products

• FreeRDP: before 3.27.0 — fixed in 3.27.0

How to fix

Upgrade to a fixed version: FreeRDP 3.27.0. Check the vendor advisory for mitigations.

References

• https://github.com/FreeRDP/FreeRDP/commit/9f2da52c2341cc14a96ad12e69c5b83d0bcd8b5a
• https://github.com/FreeRDP/FreeRDP/pull/12873
• https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.0
• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-9gxm-3mf5-f5cx

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