Is CVE-2026-9521 actively exploited?

No active exploitation of CVE-2026-9521 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-9521 be exploited remotely?

Yes. CVE-2026-9521 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-9521?

CVE-2026-9521 has a CVSS score of 7.3 (HIGH).

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HIGH

CVE-2026-9521

CWE-20Published: May 26, 2026· Updated: May 26, 2026

7.3

CVSS v3.1

EPSS:0.07%probability of exploitation in 30 daysPercentile:20.7th

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.

NVD Source

Technical Analysis

CVE-2026-9521 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.