CVE-2026-9521 fraillt bitsery std_smart_ptr.h loadFromSharedState improper validation of specified type of input
Remote attackers can exploit improper input validation in the bitsery library's smart pointer deserialization to potentially execute arbitrary code.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-9521?
CVE-2026-9521 is a medium-severity unsafe deserialization vulnerability in fraillt bitsery, published on 26 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A security vulnerability has been detected in fraillt bitsery up to 5.2.4. Affected is the function loadFromSharedState in the library include/bitsery/ext/std_smart_ptr.h. Such manipulation leads to improper validation of specified type of input. It is possible to launch the attack remotely. The exploit has been disclosed publicly and may be used. Upgrading to version 5.2.5 is able to address this issue. The name of the patch is 66d16516e24893bebc1c8af52bf2fe9ad0735061. Upgrading the affected component is advised.
Which versions are affected by CVE-2026-9521?
How do I fix CVE-2026-9521?
No fix has been published for CVE-2026-9521 yet. Limit exposure of the affected software until one is available.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-9521 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-9521 exists.
Sources
Also known as GHSA-xvwh-vh35-wwv2.