FreeRDP 3.0.0 before 3.32.2 Denial of Service via Slow-Path Input Event
Affects FreeRDP server builds 3.0.0 through 3.32.1 where WINPR_ASSERT is active, reachable through an active RDP session. Fixed in 3.32.2.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- Proof of concept public, per CISA
- 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 3.0.0 through 3.32.1 (fixed in 3.32.2) Server build has WINPR_ASSERT active (WITH_VERBOSE_WINPR_ASSERT=ON or ordinary assertions enabled) Attacker must have an active RDP session with the server (input is dispatched only after session activation)
- Exploitation15/40CISA rates a proof of concept as public
- Exposure15/25Specific setups only, CISA rates it automatable
- Reach?/20Reach: unknown (data gap). No tracked technology or package matched
- Severity8.7/10CVSS 8.7
- No patch0/5No signal
What would change the score
- Would score about 74 if added to CISA KEV
- Would score about 69 if CISA's SSVC rates exploitation active
CVE-2026-121951 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.7 (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- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean?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? →
- 39/100 · 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: poc
- Automatable: yes
- Technical impact: partial
Summary
FreeRDP, the open-source Remote Desktop Protocol library, has a flaw in how its server handles certain input events. A remote attacker can reach it over the network without logging in, by sending a malformed input event during an active session, which can crash the server process and cause a denial of service.
Read the original description
FreeRDP 3.0.0 before 3.32.2 server-side RDP peer input parsing skips the six-byte body of a slow-path input event with an unknown message type without checking it lies within the packet's declared length, causing a WinPR stream assertion failure. A remote RDP client with an active session can send a truncated unknown input event to abort assertion-enabled server processes, causing denial of service.
What to do
Check whether your setup matches what the bug needs.
Affected FreeRDP versions 3.0.0 through 3.32.1 (fixed in 3.32.2) Server build has WINPR_ASSERT active (WITH_VERBOSE_WINPR_ASSERT=ON or ordinary assertions enabled) Attacker must have an active RDP session with the server (input is dispatched only after session activation)Upgrade to a fixed version: 3.32.2.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: poc · Automatable: yes · Technical impact: partial
- Record last updated
Affected versions
- FreeRDP FreeRDP
From 3.0.0 · 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-2026-121951
Is CVE-2026-121951 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. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
A remote client with an active RDP session can send a slow-path input event that makes the FreeRDP server process abort, which terminates the server and its other sessions. The reproduction shows process termination only, with no confidentiality loss, integrity loss, or memory corruption demonstrated.Source: github.com
Which versions are affected by CVE-2026-121951?
FreeRDP: from 3.0.0 before 3.32.2.Source: cve.now feed data
Am I affected, and how do I check?
FreeRDP versions 3.0.0 through 3.32.1 are affected, but only in builds where WINPR_ASSERT is active, either with WITH_VERBOSE_WINPR_ASSERT=ON or with ordinary assertions enabled. Input is dispatched only after session activation, so the setup requires an active RDP session with the server. Check the installed FreeRDP version and whether the server build has those assertion settings enabled.Source: github.com
How do I fix CVE-2026-121951?
Upgrade to FreeRDP 3.32.2, the version that fixes this issue.Source: github.com