Improper Input Validation in Fraillt Bitsery Affects Remote Operations
CVE-2026-9521

6.3MEDIUM

Key Information:

Vendor

Fraillt

Status
Bitsery
Vendor
CVE Published:
26 May 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-9521?

A security vulnerability in Fraillt Bitsery versions up to 5.2.4 allows improper validation of specified types of input in the loadFromSharedState function of std_smart_ptr.h. This flaw can be exploited remotely, making it a critical concern for users. It has been publicly disclosed, and an upgrade to version 5.2.5, which includes the patch identified as 66d16516e24893bebc1c8af52bf2fe9ad0735061, is strongly recommended to rectify the issue and bolster security.

Affected Version(s)

bitsery 5.2.0

bitsery 5.2.1

bitsery 5.2.2

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-9521 - Proof of Concept

References

https://vuldb.com/vuln/365541
vdb-entrytechnical-description
https://vuldb.com/vuln/365541/cti
signaturepermissions-required
https://vuldb.com/submit/814457
third-party-advisory

CVSS V4

Score:
6.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
Low
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

trebledj (VulDB User)
.