# CVE-2026-121395: FreeRDP RemoteFX differential decoder assertion failure

Source: https://junglewise.ai/threats/cve-2026-121395-freerdp-from-3-17-0-before-3-32-2-contains-an-assertion-failure  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-03. Updated: 2026-11-03  
License: CC BY 4.0 with a link back

CVE-2026-121395 · Severity: medium · CVSS 6.5 · Published 2026-11-03

FreeRDP is a remote desktop protocol client used to connect to Windows systems. A malicious RDP server can craft a specially-designed RemoteFX graphics tile that causes the FreeRDP client to crash when verbose assertions are enabled, denying the user access to their remote desktop session.

Technologies: [FreeRDP](https://junglewise.ai/threats/technologies/freerdp). Vendors: [FreeRDP](https://junglewise.ai/threats/vendors/freerdp).

## 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

## References

- [https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-cg4f-57hc-v7w7](https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-cg4f-57hc-v7w7)
- [https://www.vulncheck.com/advisories/freerdp-3.17.0-before-3.32.2-denial-of-service-via-remotefx-decoder](https://www.vulncheck.com/advisories/freerdp-3.17.0-before-3.32.2-denial-of-service-via-remotefx-decoder)

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