7.5High
CVE-2026-91955
FreeRDP before 3.31.0 fails to validate client-supplied DesktopWidth and DesktopHeight values during GCC negotiation, allowing remote attackers to crash the server. Attackers can send crafted RDP packets with zero or oversized dimensions to trigger division-by-zero or assertion failures in multifragment update capability calculations, terminating the server process.
What this means for your business
- An attacker can use it remotely, over a network, without a login, and without anyone at your company clicking anything.
What to do
- 1Ask your IT team or provider whether any of your systems use the affected product.
- 2If you do, follow the vendor's guidance. No patch reference has been published yet.
Not sure if your company is exposed?
Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.
Scoring
- CVSS
- 7.5 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- CVSS v4
- 8.2
- Weakness
- CWE-369
- Assigned by
- disclosure@vulncheck.com
Dates
- Published
- 2026-09-15
- Last modified
- 2026-09-16
- Sources
- NVD