Escape Sequence Injection vulnerability in Rack lead to Possible Log Injection

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X · score source

EPSS

• CVE-2025-27111: 0.75% estimated exploitation activity in the next 30 days; percentile 55.02 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

4 Mar 2025, 15:27 UTC

Last modified by the source

4 Nov 2025, 16:55 UTC

Source last checked

26 Oct 2026, 15:51 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-8cgq-6mh2-7j6v

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# Patch Next advisory brief: CVE-2025-27111

Advisory: Escape Sequence Injection vulnerability in Rack lead to Possible Log Injection
IDs: CVE-2025-27111, GHSA-8cgq-6mh2-7j6v
Record: https://patchnext.com/advisories/cve-2025-27111 (revision 1, source checked 26 Oct 2026, 15:51 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: rack 3.1.11, 3.0.13, 2.2.12. A vendor fix does not mean a deployment is fixed.

## Affected components
- RubyGems rack: affected < 2.2.12; >= 3.0, < 3.0.13; >= 3.1, < 3.1.11; fixed in 3.1.11, 2.2.12, 3.0.13

## Suggested inspection (read-only)
- RubyGems rack: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on rack.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-8cgq-6mh2-7j6v (GitHub-reviewed advisory GHSA-8cgq-6mh2-7j6v lists affected ranges: RubyGems rack >=0 =3.0 =3.1 <3.1.11)

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