Active Support: Possible DoS vulnerability in Active Support safe_constantize

Check whether my systems are affected by CVE-2026-126080 (Active Support: Possible DoS vulnerability in Active Support safe_constantize), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-126080 (entry last updated 2026-11-10):
Affected:
- rails rails: from 8.1, fixed in 8.1.4.1; fixed in 8.0.5.2
- RubyGems package activesupport: from 8.1.0.beta1, fixed in 8.1.4.1
- RubyGems package activesupport: fixed in 8.0.5.2
Fixed versions: 8.1.4.1, 8.0.5.2.
Conditions (all must be true for the bug to be hit):
- Application mounts Action Cable, which a new Rails application does by default at /cable (source: https://github.com/rails/rails/security/advisories/GHSA-8474-xrp6-wh69)
- Application accepts Action Cable connections from untrusted clients without an added authentication check (source: https://github.com/rails/rails/security/advisories/GHSA-8474-xrp6-wh69)
- ActiveSupport versions before 8.0.5.2, or 8.1 before 8.1.4.1 (source: https://github.com/rails/rails/security/advisories/GHSA-8474-xrp6-wh69)
Setup: the bug is reachable in a default setup; no special feature or setting is needed.
Attacker needs: network access, no login, no user action.
Workaround: Set config.action_cable.mount_path = nil if Action Cable is not used; otherwise reject unauthenticated connections in ApplicationCable::Connection#connect, which does not remove the exposure. (source: https://github.com/rails/rails/security/advisories/GHSA-8474-xrp6-wh69)
CISA KEV: CVE-2026-126080 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126080 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Packages (RubyGems): find every lockfile in each project and run check_stack from the cve.now MCP server on each one. Compare the resolved versions, not the ranges a manifest declares, with the affected versions above. Include transitive dependencies.
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/rails/rails/security/advisories/GHSA-8474-xrp6-wh69
- https://github.com/rails/rails/commit/210ac22d446c8e2625b091e79256806b836eee20
- https://github.com/rails/rails/commit/95aa9e416016524956d4904fed96eaed079580bb
- https://github.com/rails/rails/releases/tag/v8.0.5.2
- https://github.com/rails/rails/releases/tag/v8.1.4.1
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-126080
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-126080.