# CVE-2026-121404: FreeRDP denial of service in shadow server dynamic-channel handling

Source: https://junglewise.ai/threats/cve-2026-121404-freerdp-before-3-32-2-contains-a-denial-of-service-vulnerability  
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-2026-121404 · Severity: medium · CVSS 6.5 · Published 2026-11-03

FreeRDP's shadow server is a remote desktop protocol implementation used to enable remote access to systems. An authenticated RDP client can exhaust CPU resources by sending specially-crafted zero-length messages on audio or graphics channels, causing server threads to spin until the client disconnects. This is a denial of service attack available only to authenticated users.

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

## Quick answers

**Is CVE-2026-121404 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-121404 being exploited in the wild.

**How severe is CVE-2026-121404?** Medium severity, with a CVSS score of 6.5, published 3 November 2026.

**Which products and versions are affected?** FreeRDP before 3.32.2.

**Is there a fix for CVE-2026-121404?** Yes: fixed in 3.32.2. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-121404 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-121404?** 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

## Technical details

The vulnerability exists in wts_read_drdynvc_data (libfreerdp/core/server.c) which queues DATA payloads even when the payload is zero-length. FreeRDP_WTSVirtualChannelRead peeks without consuming empty messages, causing the audin and rdpgfx channel readers to loop continuously consuming CPU. The attack requires an authenticated RDP connection and the specific channel (audin or rdpgfx) to be open, and is fixed in version 3.32.2.

## Affected products

- FreeRDP FreeRDP before 3.32.2

## Timeline

- 2026-10-19: disclosed: GitHub Security Advisory published
- 2026-11-03: advisory: NVD and public advisories published

## References

- [https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-fqcj-rwww-2498](https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-fqcj-rwww-2498)
- [https://www.vulncheck.com/advisories/freerdp-before-3.32.2-shadow-server-cpu-exhaustion-via-zero-length-dvc-data](https://www.vulncheck.com/advisories/freerdp-before-3.32.2-shadow-server-cpu-exhaustion-via-zero-length-dvc-data)

## Related threats

- [FreeRDP heap use-after-free in brush cache](https://junglewise.ai/threats/cve-2026-125394-freerdp-before-3-33-0-contains-a-heap-use-after-free)
- [FreeRDP heap buffer overflow in RD Gateway RPC client](https://junglewise.ai/threats/cve-2026-121964-freerdp-before-3-32-2-contains-a-heap-based-buffer-overflow-in)
- [FreeRDP use-after-free in dynamic rdpsnd channel](https://junglewise.ai/threats/cve-2026-121963-freerdp-before-3-32-2-contains-a-use-after-free-vulnerability-in)
- [FreeRDP denial of service in NLA shadow server via malformed TSRequest](https://junglewise.ai/threats/cve-2026-121960-freerdp-before-3-32-2-contains-a-denial-of-service-vulnerability)
- [FreeRDP heap out-of-bounds write in RDPGFX HashTable_GetKeys](https://junglewise.ai/threats/cve-2026-121958-freerdp-through-3-32-1-has-a-heap-out-of-bounds-write-in-the)