Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS
CVE-2026-121957 Overview
FreeRDP before 3.32.2 contains a use-after-free vulnerability that allows malicious RDP servers to corrupt client memory by racing the RDPGFX ResetGraphics handler against the planar bitmap decoder. Attackers can send ResetGraphics while concurrently sending compressed bitmaps of 32 bpp or more to trigger heap use-after-free or out-of-bounds read/write on shared planar buffers.
Critical Impact
Affected Products
- FreeRDP: see the vendor advisory for the exact affected versions
Discovery Timeline
- 2026-11-04: CVE-2026-121957 published to the National Vulnerability Database by disclosure@vulncheck.com
- 2026-11-04: last updated in the NVD database
Technical Details for CVE-2026-121957
Vulnerability Analysis
CVE-2026-121957 is a Race Condition weakness (CWE-362: Race Condition) in FreeRDP. Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Two operations collide in timing, breaking a security assumption.
With a CVSS base score of 8.7, apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Root Cause
The weakness is classified as CWE-362: Race Condition. Two operations collide in timing, breaking a security assumption.
Attack Vector
Based on the CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Attack complexity is low complexity.
No exploitation in the wild is confirmed by CISA at the time of the last update. Check the references below for any vendor or researcher proof of concept.
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
Detection Methods for CVE-2026-121957
Detection Strategies
- Inventory every instance of FreeRDP and compare the running version with the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Run an authenticated vulnerability scan once your scanner ships a check for this CVE.
Monitoring Recommendations
- Forward FreeRDP application, access and audit logs to your SIEM for retrospective hunting.
- Alert on new processes, configuration changes or outbound connections from the affected service.
- Track the vendor advisory and the CISA KEV catalog for changes in exploitation status.
How to Mitigate CVE-2026-121957
Immediate Actions Required
- Apply the fixed version of FreeRDP named in the vendor advisory.
- Prioritize internet facing and business critical instances first.
- Rescan after the change to confirm the exposure is closed.
Patch Information
Use the fixed version listed in the vendor advisory for FreeRDP.
Workarounds
- If patching must wait, restrict network access to the affected service and place it behind authentication or a web application firewall rule.
CWE References
- CWE-362: Race Condition More CVEs with this weakness
Technical References
This entry is built directly from NVD, CISA KEV and EPSS data. Verify fixed versions in the vendor advisory before you deploy.
Frequently asked questions
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