FreeRDP shadow server lets clients exhaust CPU with empty messages
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 2 fixed, 4 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-400.
Summary
FreeRDP before 3.32.2 has a denial of service flaw in its shadow server. The server does not consume zero-length drdynvc DATA messages sent on opened audin or rdpgfx channels, so its threads spin with CWE-400 uncontrolled resource consumption. An authenticated remote RDP client with low privileges can consume full CPU cores until it disconnects.
Written with Claude Haiku 5.5 from the sources below · 2026-11-04
Description from the CNA
FreeRDP before 3.32.2 contains a denial of service vulnerability in the shadow server that allows authenticated RDP clients to spin server threads by sending zero-length drdynvc DATA PDUs. Attackers can send empty DATA messages on opened audin or rdpgfx channels, so that FreeRDP_WTSVirtualChannelRead never consumes them, consuming full CPU cores until disconnect.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
Update FreeRDP to version 3.32.2. Red Hat fixes this in Red Hat Enterprise Linux AppStream (version 10) and CodeReady Linux Builder (version 10) with advisory RHSA-2026:94514. Red Hat has no fix planned for Red Hat Enterprise Linux 6, 7, 8 and 9.
Written with Claude Haiku 5.5 from the sources below · 2026-11-04
- Fix · CNA FreeRDP (FreeRDP) Fixed in 3.32.2
Red Hat 1 advisory
- RHSA-2026:94514 Released 2026-11-03 · Red Hat rating Importantfreerdp security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream (v. 10) freerdp-2:3.32.2-1.el10_2, freerdp-libs-2:3.32.2-1.el10_2, libwinpr-2:3.32.2-1.el10_2
- Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) freerdp-devel-2:3.32.2-1.el10_2, freerdp-server-2:3.32.2-1.el10_2, libwinpr-devel-2:3.32.2-1.el10_2
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
FreeRDP 3.32.2
27 records Highest priority Priority HIGH 3 HIGH, 11 MEDIUM, 13 LOW
Other records, highest priority first
- TI-2026-84268 Denial of service in FreeRDP WinPR PNG and JPEG image readersPriority HIGH 77
- TI-2026-84291 Denial of service in FreeRDP via oversized X.224 routing tokenPriority HIGH 69
- TI-2026-84280 Use-after-free in FreeRDP dyn-channel-dump modulePriority HIGH 69
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AppStream (v. 10) | Fixed | RHSA-2026:94514 |
| Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) | Fixed | RHSA-2026:94514 |
Timeline
- 2026-11-03 Threatist record created from CVE-2026-121404
- 2026-11-03 Alias added: GHSA-26v7-mr7m-fqqx
- 2026-11-03 CISA SSVC decision points changed
- 2026-11-03 Priority changed: MEDIUM → LOW
- 2026-11-04 Affected versions changed · Red Hat
- 2026-11-04 CVSS score added · Red Hat
- 2026-11-04 Fix available: RHSA-2026:94514 · Red Hat
- 2026-11-04 Fix available: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) · Red Hat
References
More Freerdp vulnerabilities
- TI-2026-85092 Use-after-free in FreeRDP rdpgfx channel close handling CVSS 4.0CRITICAL 9.3
- TI-2026-85091 Out-of-bounds write in FreeRDP proxy via bitmap cache v2 capability CVSS 4.0CRITICAL 9.3
- TI-2026-24435 FreeRDP has a `size_t` underflow in ADPCM decoder leads to heap-buffer-overflow write CVSS 3.1CRITICAL 9.8
- TI-2023-21373 Out-Of-Bounds Write in FreeRDP CVSS 3.1CRITICAL 9.8
- TI-2022-08692 Server side NTLM does not properly check parameters in FreeRDP CVSS 3.1CRITICAL 9.1
- TI-2023-21374 Out-Of-Bounds Read in FreeRDP CVSS 3.1CRITICAL 9.1
Sources
- CVE-2026-121404 · CVE Program
- CVE-2026-121404 · NVD
- FIRST EPSS
- GHSA-26v7-mr7m-fqqx · GitHub Advisory Database · CC BY 4.0
- CVE-2026-121404 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences