CVE-2026-22858 FreeRDP has a global-buffer-overflow in crypto_base64_decode
A global buffer overflow in FreeRDP's Base64 decoder allows attackers to cause out-of-bounds access, potentially leading to code execution or crashes.
- 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-2026-22858?
CVE-2026-22858 is a medium-severity memory corruption vulnerability in Freerdp Freerdp, published on 14 Jan 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 3.20.1, global-buffer-overflow was observed in FreeRDP's Base64 decoding path. The root cause appears to be implementation-defined char signedness: on Arm/AArch64 builds, plain char is treated as unsigned, so the guard c <= 0 can be optimized into a simple c != 0 check. As a result, non-ASCII bytes (e.g., 0x80-0xFF) may bypass the intended range restriction and be used as an index into a global lookup table, causing out-of-bounds access. This vulnerability is fixed in 3.20.1.
Which versions are affected by CVE-2026-22858?
It affects 1 product.
Products include Freerdp Freerdp.
How do I fix CVE-2026-22858?
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-2026-22858 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-22858 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-2026-22858, GHSA-qmqf-m84q-x896, MINI-rjw5-38f3-3hfr, UBUNTU-CVE-2026-22858.