CVE-2026-33986 FreeRDP: H.264 YUV Buffer Dimension Desync - Heap OOB Write
A heap out-of-bounds write in FreeRDP's H.264 decoder allows attackers to execute arbitrary code or cause denial of service via crafted RDP traffic.
- 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-2026-33986?
CVE-2026-33986 is a high-severity memory corruption 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, in yuv_ensure_buffer() in libfreerdp/codec/h264.c, h264->width and h264->height are updated before the reallocation loop. If any winpr_aligned_recalloc() call fails, the function returns FALSE but width/height are already inflated. This issue has been patched in version 3.24.2.
Which versions are affected by CVE-2026-33986?
It affects 1 product.
Products include Freerdp Freerdp.
How do I fix CVE-2026-33986?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-33986 being exploited?
There is no known exploitation of CVE-2026-33986 in the wild and no public exploit code.
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-2026-33986, GHSA-h6qw-wxvm-hf97, UBUNTU-CVE-2026-33986.