Buffer overflow in Freerdp
CVE-2026-91953
FreeRDP versions before 3.31.0 contain a heap buffer overflow vulnerability in nego_send_negotiation_request() that fails to validate the LB_LOAD_BALANCE_INFO field length before writing to a fixed 512-byte buffer. A malicious RDP server or man-in-the-middle can send a Server Redirection PDU with an oversized LB_LOAD_BALANCE_INFO value to overflow the buffer with attacker-controlled content, causing denial of service or heap corruption before authentication completes.
Vulnerability class: Buffer Overflow
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.
Affected products
Weakness classification (CWE)
References
- disclosure@vulncheck.com (vendor-advisory)
- disclosure@vulncheck.com (third-party-advisory)
Frequently asked questions
- What is CVE-2026-91953?
- CVE-2026-91953 is a medium-severity vulnerability in Freerdp, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 6.5/10. Published 2026-09-15.
- How severe is CVE-2026-91953?
- Medium severity. CVSS v3 base score is 6.5 out of 10.