Single-Factor Authentication Vulnerability in Umami by Umami Software
CVE-2026-121531

5.3MEDIUM

Key Information:

Vendor

Umami Software

Status
Umami
Vendor
CVE Published:
3 November 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-121531?

A vulnerability has been identified in Umami versions 3.3.x, 3.4.0, and 3.4.1, specifically within the 2FA Policy Handler component located at src/app/api/auth/login/route.ts. This flaw allows attackers to bypass two-factor authentication, reverting to single-factor authentication mechanisms. The exploit can be executed remotely, posing a significant risk to users' accounts. Despite early contact with the vendor regarding the vulnerability, no response was received, heightening concerns about the potential exploitation of this vulnerability.

Affected Version(s)

Umami 3.3.*

Umami 3.4.0

Umami 3.4.1

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-2026-121531 - Proof of Concept

References

https://vuldb.com/vuln/430290
vdb-entry
https://vuldb.com/vuln/430290/cti
signaturepermissions-required
https://vuldb.com/cve/CVE-2026-121531
third-party-advisory

CVSS V4

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

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

waterhunter (VulDB User)
VulDB CNA Team
.