CVE-2025-27111 — rack
Fix: rack/rack@803aa22CVE-2025-27111 is a CWE-93 vulnerability in rack. A fix is available for rack — see the affected versions and patch details below.
Escape Sequence Injection vulnerability in Rack lead to Possible Log Injection
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-27111.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
rack💎rack💎rackReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Rack::Sendfile can be exploited by crafting input that includes newline characters to manipulate log entries.
Details
The Rack::Sendfile middleware logs unsanitized header values from the X-Sendfile-Type header. An attacker can exploit this by injecting escape sequences (such as newline characters) into the header, resulting in log injection.
Impact
This vulnerability can distort log files, obscure attack traces, and complicate security auditing.
Mitigation
- Update to the latest version of Rack, or
- Remove usage of
Rack::Sendfile.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | rack | all versions | 2.2.12bundle update rack --conservative |
| 💎RubyGems | rack | ≥ 3.0&&< 3.0.13 | 3.0.13bundle update rack --conservative |
| 💎RubyGems | rack | ≥ 3.1&&< 3.1.11 | 3.1.11bundle update rack --conservative |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rack, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update rack to 2.2.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-27111 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-27111 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-27111. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Frequently Asked Questions
Is CVE-2025-27111 in your dependencies?
O3 Security finds CVE-2025-27111 across RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.