What’s Vulnerable › Vulnerabilities

CVE-2026-91953: FreeRDP before 3.31.0 Heap Buffer Overflow via LB_LOAD_BALANCE_INFO

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-09-15 · updated 2026-09-24
• Weakness: CWE-120

Description

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.

Affected products

• FreeRDP: before 3.31.0 — fixed in 3.31.0

How to fix

Upgrade to a fixed version: FreeRDP 3.31.0. Check the vendor advisory for mitigations.

References

• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-r9pv-ffph-6gg6
• https://www.vulncheck.com/advisories/freerdp-before-3.31.0-heap-buffer-overflow-via-lb-load-balance-info

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