GHSA-336F-J5CQ-6C4F
Vulnerability from github – Published: 2026-08-11 15:32 – Updated: 2026-08-11 15:32FreeRDP before 3.30.0 contains a server-side authentication bypass in the RDSTLS handshake. When a server is configured with RdstlsSecurity = TRUE, the handshake dispatches inbound PDUs based solely on the attacker-supplied wire pduType without verifying that the received PDU is the one required at the current step. Because the rdpRdstls object is calloc-zeroed, its resultCode defaults to 0 (RDSTLS_RESULT_SUCCESS). An unauthenticated remote client can send a Capabilities PDU instead of the required Authentication Request PDU; rdstls_process_capabilities() returns success without ever setting resultCode, so the server responds with an AUTHRSP carrying resultCode SUCCESS and treats the session as authenticated without evaluating any password, redirection GUID, or auto-reconnect cookie. This affects the released FreeRDP 3.x series (e.g., 3.27.1) and master HEAD; at the time of the advisory no patched version was available.
{
"affected": [],
"aliases": [
"CVE-2026-72746"
],
"database_specific": {
"cwe_ids": [
"CWE-287"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-11T13:19:05Z",
"severity": "HIGH"
},
"details": "FreeRDP before 3.30.0 contains a server-side authentication bypass in the RDSTLS handshake. When a server is configured with RdstlsSecurity = TRUE, the handshake dispatches inbound PDUs based solely on the attacker-supplied wire pduType without verifying that the received PDU is the one required at the current step. Because the rdpRdstls object is calloc-zeroed, its resultCode defaults to 0 (RDSTLS_RESULT_SUCCESS). An unauthenticated remote client can send a Capabilities PDU instead of the required Authentication Request PDU; rdstls_process_capabilities() returns success without ever setting resultCode, so the server responds with an AUTHRSP carrying resultCode SUCCESS and treats the session as authenticated without evaluating any password, redirection GUID, or auto-reconnect cookie. This affects the released FreeRDP 3.x series (e.g., 3.27.1) and master HEAD; at the time of the advisory no patched version was available.",
"id": "GHSA-336f-j5cq-6c4f",
"modified": "2026-08-11T15:32:37Z",
"published": "2026-08-11T15:32:37Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-rqgv-grx4-xm6x"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72746"
},
{
"type": "WEB",
"url": "https://github.com/FreeRDP/FreeRDP/commit/b05a9510787c83c87ffc5fa8d7cc9f06ed971695"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/freerdp-before-rdstls-server-authentication-bypass-via-pdu-type-confusion"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/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:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
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