Possible Log Injection in Rack::CommonLogger
## Summary `Rack::CommonLogger` can be exploited by crafting input that includes newline characters to manipulate log entries. The supplied proof-of-concept demonstrates injecting malicious content into logs. ## Details When a user provides the authorization credentials via `Rack::Auth::Basic`, if success, the username will be put in `env['REMOTE_USER']` and later be used by `Rack::CommonLogger` for logging purposes. The issue occurs when a server intentionally or unintentionally allows a user creation with the username contain CRLF and white space characters, or the server just want to log every login attempts. If an attacker enters a username with CRLF character, the logger will log the malicious username with CRLF characters into the logfile. ## Impact Attackers can break log formats or insert fraudulent entries, potentially obscuring real activity or injecting malicious data into log files. ## Mitigation - Update to the latest version of Rack.
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2025-25184US | medium6.5 | — | ||
Rack provides an interface for developing web applications in Ruby. Prior to versions 2.2.11, 3.0.12, and 3.1.10, Rack::CommonLogger can be exploited by crafting input that include… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/rack/rackPACKAGE
- https://github.com/rack/rack/commit/074ae244430cda05c27ca91cda699709cfb3ad8eWEB
- https://github.com/rack/rack/security/advisories/GHSA-7g2v-jj9q-g3rgWEB
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rack/CVE-2025-25184.ymlWEB
- https://lists.debian.org/debian-lts-announce/2025/03/msg00016.htmlWEB
- https://nvd.nist.gov/vuln/detail/CVE-2025-25184ADVISORY
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