EUVD-2026-56135
GHSA-9q6x-42cw-m8jx
Severity by source
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
Network-reachable pre-authentication; EC field misuse yields OOB heap read and write, covering confidentiality, integrity, and availability impacts.
Primary rating from Vendor (VulnCheck).
CVSS VectorVendor: VulnCheck
Lifecycle Timeline
3DescriptionCVE.org
FreeRDP before 3.30.0 contains an out-of-bounds vulnerability in kerberos_DecryptMessage() (winpr/libwinpr/sspi/Kerberos/kerberos.c). The 16-bit EC (extra count) field of a peer-supplied GSS Wrap token (RFC 4121) is used directly in pointer arithmetic to locate the encrypted regions without being bounds-checked, while only RRC and the total buffer length are validated. A malicious peer (server or client) can supply a large EC value (up to 0xFFFF) during CredSSP/NLA authentication, moving the decrypt operation's base pointers past the end of the ~60-byte token buffer. Because the AES-CTS-HMAC enctypes decrypt in place before the HMAC integrity check, this results in an out-of-bounds read and in-place out-of-bounds write, potentially leading to information disclosure, memory corruption, or denial of service.
AnalysisAI
Heap-based out-of-bounds read and write in FreeRDP before 3.30.0 can be triggered by a malicious peer during CredSSP/NLA Kerberos authentication, allowing information disclosure, heap memory corruption, or denial of service. The flaw exists in kerberos_DecryptMessage() where the peer-supplied 16-bit EC field of a GSS Wrap token is used directly in pointer arithmetic without bounds validation, enabling any RDP peer - rogue server or malicious client - to shift decrypt pointers up to 65535 bytes past the end of a ~60-byte token buffer. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires that the targeted FreeRDP endpoint is configured to use Kerberos-based CredSSP/NLA authentication - a common enterprise configuration. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The vendor-supplied CVSS 4.0 score of 8.7 (AV:N/AC:L/AT:N/PR:N/UI:N) accurately reflects network reachability with no authentication prerequisite, since the flaw fires during the authentication handshake itself. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Upgrade FreeRDP to version 3.30.0 or later, which resolves the missing EC field bounds check per the vendor advisory at https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-vv64-95pc-vj9v. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, conduct inventory of systems running FreeRDP versions below 3.30.0 and evaluate network exposure of RDP services. …
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FreeRDP is a free implementation of the Remote Desktop Protocol. Rated critical severity (CVSS 9.8), this vulnerability
FreeRDP is a free implementation of the Remote Desktop Protocol (RDP), released under the Apache license. Rated critical
FreeRDP is a free implementation of the Remote Desktop Protocol (RDP), released under the Apache license. Rated critical
FreeRDP is a free implementation of the Remote Desktop Protocol (RDP), released under the Apache license. Rated critical
Same weakness CWE-122 – Heap-based Buffer Overflow
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External POC / Exploit Code
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