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
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.005 (40.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 40.7% 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: 0.005 · change: +0.000
Affected products
Weakness classification (CWE)
References
- github.com/FreeRDP/FreeRDP/security/advisories/GHSA-r9pv-ffph-6gg6 (Exploit, vendor-advisory, Mitigation, Vendor Advisory)
- www.vulncheck.com/advisories/freerdp-before-3.31.0-heap-buffer-overflow-via-lb-… (Third Party Advisory, 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.