FreeRDP before 3.32.2 Shadow Server CPU Exhaustion via Zero-Length DVC DATA
Affects FreeRDP before 3.32.2 when the shadow server runs with an audin or rdpgfx dynamic channel opened by the client. Fixed in 3.32.2.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 3.32.2
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Affected FreeRDP versions are before 3.32.2 (advisory lists affected versions as 3.32.1 and earlier). The FreeRDP shadow server must be running with a dynamic channel (audin or rdpgfx) opened by the client. Stock shadow starts the audin reader per client and rdpgfx when graphics is negotiated.
- Exploitation0/40No signal
- Exposure8/25Specific setups only, reachable over the network
- Reach?/20Reach: unknown (data gap). No tracked technology or package matched
- Severity7.1/10CVSS 7.1
- No patch0/5No signal
What would change the score
- Would score about 65 if added to CISA KEV
- Would score about 60 if CISA's SSVC rates exploitation active
- Would score about 22 if CISA's SSVC rates it automatable
CVE-2026-121404 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.1 (high) and affects FreeRDP; fixed in 3.32.2.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 15/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 3.32.2
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
FreeRDP, a widely used open-source Remote Desktop Protocol library, is affected in its shadow server component. A logged-in remote client can send specially crafted empty messages that cause server threads to consume entire CPU cores until the connection is closed, resulting in a denial of service.
Read the original description
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.
What to do
Check whether your setup matches what the bug needs.
Affected FreeRDP versions are before 3.32.2 (advisory lists affected versions as 3.32.1 and earlier). The FreeRDP shadow server must be running with a dynamic channel (audin or rdpgfx) opened by the client. Stock shadow starts the audin reader per client and rdpgfx when graphics is negotiated.Upgrade to a fixed version: 3.32.2.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- FreeRDP FreeRDP
fixed in 3.32.2
Evidence 2
- Advisory
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-121404
Is CVE-2026-121404 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
A remote authenticated RDP client can make the FreeRDP shadow server spin server threads, consuming full CPU cores until the client disconnects. This is a denial of service.Source: vulncheck.com, github.com
Which versions are affected by CVE-2026-121404?
FreeRDP: before 3.32.2.Source: cve.now feed data
Am I affected, and how do I check?
Versions before 3.32.2, which the advisory lists as 3.32.1 and earlier. The issue involves the shadow server with an audin or rdpgfx dynamic channel opened by the client; stock shadow starts audin per client and rdpgfx when graphics is negotiated. Check the installed FreeRDP version and whether the shadow server is in use.Source: vulncheck.com, github.com
How do I fix CVE-2026-121404?
Upgrade FreeRDP to 3.32.2 or later, the version that fixes this issue.Source: vulncheck.com, github.com