Buffer overflow in Freerdp
CVE-2026-55194
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.006 (47.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 47.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.002
Affected products
- Freerdp — versions < 3.27.0
Weakness classification (CWE)
References
- github.com/FreeRDP/FreeRDP/security/advisories/GHSA-9gxm-3mf5-f5cx (Exploit, Mitigation, Vendor Advisory)
- github.com/FreeRDP/FreeRDP/pull/12873 (Patch, Issue Tracking)
- github.com/FreeRDP/FreeRDP/commit/9f2da52c2341cc14a96ad12e69c5b83d0bcd8b5a (Patch)
- github.com/FreeRDP/FreeRDP/releases/tag/3.27.0 (Release Notes)
Frequently asked questions
- What is CVE-2026-55194?
- CVE-2026-55194 is a critical-severity vulnerability in Freerdp, classified under Heap-based Buffer Overflow. CVSS score: 9.8/10. Published 2026-08-19.
- How severe is CVE-2026-55194?
- Critical severity. CVSS v3 base score is 9.8 out of 10.