Quick answers
- Is CVE-2026-121395 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-121395 being exploited in the wild.
- How severe is CVE-2026-121395?
- Medium severity, with a CVSS score of 6.5, published 3 November 2026.
- Which products and versions are affected?
- FreeRDP 3.17.0 before 3.32.2.
- Is there a fix for CVE-2026-121395?
- Yes: fixed in 3.32.2. Until then: Disable RemoteFX support or ensure FreeRDP is built without verbose WinPR assertions (WITH_VERBOSE_WINPR_ASSERT=OFF) until an upgrade is available. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-121395 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-121395?
- Check whether you run FreeRDP at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: 3.32.2
Disable RemoteFX support or ensure FreeRDP is built without verbose WinPR assertions (WITH_VERBOSE_WINPR_ASSERT=OFF) until an upgrade is available.
Technical details
The RemoteFX differential decoder in FreeRDP contains an assertion that checks whether the sum of two adjacent LL3 coefficients fits within a signed 16-bit range. An attacker can send a crafted tile with coefficients that sum beyond this range (e.g., 20,000 + 20,000 = 40,000), triggering the assertion failure. This requires the client to connect to the attacker-controlled RDP server and have WinPR verbose assertions enabled at build time (WITH_VERBOSE_WINPR_ASSERT=ON).
Affected products
- FreeRDP FreeRDP 3.17.0 before 3.32.2
Timeline
- 2026-10-19: disclosed
- 2026-11-03: advisory