Cross-Site Scripting Vulnerability in Blitz.js Affecting Login Functionality
CVE-2026-9520

5.3MEDIUM

Key Information:

Vendor

Blitz-js

Status
Blitz
Vendor
CVE Published:
26 May 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-9520?

A Cross-Site Scripting vulnerability has been identified within the LoginForm component of Blitz.js up to version 3.0.2. This weakness can be exploited by manipulating the argument 'Next' in the application, enabling attackers to execute arbitrary scripts in the context of a victim's browser. The attack can be initiated remotely, leading to potential unauthorized access and data theft. Publicly available exploits increase the urgency for users to review and remediate this vulnerability.

Affected Version(s)

blitz 3.0.0

blitz 3.0.1

blitz 3.0.2

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-2026-9520 - Proof of Concept

References

https://vuldb.com/vuln/365540
vdb-entrytechnical-description
https://vuldb.com/vuln/365540/cti
signaturepermissions-required
https://vuldb.com/submit/814378
third-party-advisory

CVSS V4

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

trebledj (VulDB User)
VulDB CNA Team
.