Active Support: Possible DoS vulnerability in Active Support safe_constantize
CVE-2026-126080
Impact When constant lookup raises LoadError, ActiveSupport::Inflector#safeconstantize (and String#safeconstantize) builds a regular expression from the requested constant name without escaping it, so a caller that passes untrusted input lets the attacker choose the source of a pattern that the application compiles. Crafted patterns can trigger defects in Ruby's regular expression compiler, possibly leading to a crash of the server process, and repeated requests could keep the application unavailable. Action Cable passes the channel value of each subscribe command to safeconstantize before any channel lookup, so in the default configuration an unauthenticated client of the Action Cable endpoint can reach this code. Details The check that decides whether safeconstantize returns nil or re-raises the LoadError now matches the first segment of the constant name against the error message as a literal string, and no longer compiles a regular expression. It returns the same result as before for constant names that contain no regular expression syntax. Affected applications An application is affected if it meets all of these requirements: Mounts Action Cable, which a new Rails application…
Assessment
- CVSS
- 7.5 (v3.1)
- Severity
- High
- Known exploited
- Not listed in CISA KEV
- Exploit availability
- Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
- Published
- 10 November 2026
- Last updated
- 10 November 2026
- Affected
- activesupport
- Weakness
- CWE-74
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
At the source
References
- 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
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/activesupport/GHSA-8474-xrp6-wh69.yml
- https://github.com/advisories/GHSA-8474-xrp6-wh69
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