CVE-2026-55194 FreeRDPHeap-buffer-overflow write in TS Gateway RPC RESPONSE reassembly due to alloc_hint capacity mismatch
A malicious TS Gateway can trigger a heap buffer overflow in FreeRDP, potentially allowing code execution or crashing the client.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-55194?
CVE-2026-55194 is a high-severity memory corruption vulnerability in Freerdp Freerdp, published on 19 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-122
Which versions are affected by CVE-2026-55194?
It affects 1 product.
Products include Freerdp Freerdp.
How do I fix CVE-2026-55194?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-55194 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55194 exists.
Other vulnerabilities in Freerdp Freerdp
- CVE-2021-37594 Other in n/a
- CVE-2021-37595 Other in n/a
- CVE-2026-67305 FreeRDP Windows Client before 3.29.0 Heap Buffer Overflow via Cliprdr
- CVE-2026-66402 FreeRDP before 3.29.0 TLS Certificate Identity Validation Bypass
- CVE-2026-67289 FreeRDP before 3.29.0 HTTP Proxy Request Injection via Redirection
Sources
Also known as DEBIAN-CVE-2026-55194, GHSA-9gxm-3mf5-f5cx, UBUNTU-CVE-2026-55194.