CVE-2026-33952 FreeRDP: DoS via WINPR_ASSERT in rts_read_auth_verifier_no_checks
A malicious RDP Gateway can crash FreeRDP clients via an assertion failure in the authentication verifier, causing a pre-authentication denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-33952?
CVE-2026-33952 is a medium-severity denial of service vulnerability in Freerdp Freerdp, published on 30 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.24.2, an unvalidated auth_length field read from the network triggers a WINPR_ASSERT() failure in rts_read_auth_verifier_no_checks(), causing any FreeRDP client connecting through a malicious RDP Gateway to crash with SIGABRT. This is a pre-authentication denial of service affecting all FreeRDP clients using RPC-over-HTTP gateway transport. The assertion is active in default release builds (WITH_VERBOSE_WINPR_ASSERT=ON). This issue has been patched in version 3.24.2.
Weakness: CWE-617
Which versions are affected by CVE-2026-33952?
It affects 1 product.
Products include Freerdp Freerdp.
How do I fix CVE-2026-33952?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-33952 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33952 exists.
Other vulnerabilities in Freerdp Freerdp
- CVE-2021-37594 Other in n/a
- CVE-2021-37595 Other in n/a
- CVE-2026-67305 FreeRDP Windows Client before 3.29.0 Heap Buffer Overflow via Cliprdr
- CVE-2026-66402 FreeRDP before 3.29.0 TLS Certificate Identity Validation Bypass
- CVE-2026-67289 FreeRDP before 3.29.0 HTTP Proxy Request Injection via Redirection
Sources
Also known as DEBIAN-CVE-2026-33952, GHSA-4v4p-9v5x-hc93, UBUNTU-CVE-2026-33952.