---
id: CVE-2026-67990
title: >-
  basecamp/upright at commit efe4f2e5254ac6e57e45d2261804cca74dbbca3f disables
  Rails CSRF protection for its Alertmanager and Prometheus proxy controllers
summary: >-
  basecamp/upright at commit efe4f2e5254ac6e57e45d2261804cca74dbbca3f disables
  Rails CSRF protection for its Alertmanager and Prometheus proxy controllers.
  An unauthenticated attacker can induce a logged-in user's browser to submit
  request…
severity: medium
cvss: 5.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N'
cwe:
  - CWE-352
published: '2026-08-13'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T19:42:20.313'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-67990'
references:
  - url: 'https://gist.github.com/Zykis1024/cec690012eecac53f408e78d2b569f06'
    label: cve@mitre.org
  - url: 'https://github.com/basecamp/upright'
    label: cve@mitre.org
  - url: >-
      https://github.com/basecamp/upright/blob/efe4f2e5254ac6e57e45d2261804cca74dbbca3f/app/controllers/upright/alertmanager_proxy_controller.rb#L2
    label: cve@mitre.org
  - url: >-
      https://github.com/basecamp/upright/blob/efe4f2e5254ac6e57e45d2261804cca74dbbca3f/app/controllers/upright/prometheus_proxy_controller.rb#L2
    label: cve@mitre.org
tags:
  - nvd
epss: 0.00182
epssPercentile: 0.06914
ingestedAt: '2026-09-08T20:10:03.157Z'
---

## Overview

basecamp/upright at commit efe4f2e5254ac6e57e45d2261804cca74dbbca3f disables Rails CSRF protection for its Alertmanager and Prometheus proxy controllers. An unauthenticated attacker can induce a logged-in user's browser to submit requests that are forwarded to enabled upstream write or management endpoints, such as creating an Alertmanager silence or requesting a Prometheus reload. The final impact depends on the APIs enabled by the upstream services.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.