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Vulnerability record · CVE-2026-55193 · published 19 August 2026

CVE-2026-55193: Heap-based buffer overflow vulnerability

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, FreeRDP clients using TS Gateway accept a server-controlled max_xmit_frag value in libfreerdp/core/gateway/rpc_bind.c without bounding it to the 4088-byte ReceiveFragment allocation. A malicious gateway can advertise 65535 and then send a response fragment of the same length, causing rpc_channel_read in libfreerdp/core/gateway/rpc.c to write up to 65535 bytes into the smaller ReceiveFragment buffer. This can crash the client and may permit code execution through attacker-controlled heap corruption. This issue is fixed in version 3.27.0.

8.7 CVSS 4.0 High EPSS 0.47% · top 62.0% CWE-122 · Heap-based buffer overflow Awaiting Analysis
8.7CVSS 4.0 base score
0.47%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
4References
9 Sep 2026Last modified by NVD

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, FreeRDP clients using TS Gateway accept a server-controlled max_xmit_frag value in libfreerdp/core/gateway/rpc_bind.c without bounding it to the 4088-byte ReceiveFragment allocation. A malicious gateway can advertise 65535 and then send a response fragment of the same length, causing rpc_channel_read in libfreerdp/core/gateway/rpc.c to write up to 65535 bytes into the smaller ReceiveFragment buffer. This can crash the client and may permit code execution through attacker-controlled heap corruption. This issue is fixed in version 3.27.0.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/FreeRDP/FreeRDP/commit/a863ef1cf1cdabf9019280e5658f806e73bb50e8
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-7rp4-66mc-j9vx

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Source: NIST National Vulnerability Database (record CVE-2026-55193), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.