Rack has a Possible Information Disclosure Vulnerability

Exploitation

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

CVSS

5.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N

EPSS

• CVE-2025-61780: 0.55% estimated exploitation activity in the next 30 days; percentile 46.22 (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 A possible information disclosure vulnerability existed in Rack::Sendfile when running behind a proxy that supports x-sendfile headers (such as Nginx). Specially crafted headers could cause Rack::Sendfile to miscommunicate with the proxy and trigger unintended internal requests, potentially bypassing proxy-level access restrictions. Details When Rack::Sendfile received untrusted x-sendfile-type or x-accel-mapping headers from a client, it would interpret them as proxy configuration directives. This could cause the middleware to send a "redirect" response to the proxy, prompting it to reissue a new internal request that was not subject to the proxy's access controls. An attacker could exploit this by: 1. Setting a crafted x-sendfile-type: x-accel-redirect header. 2. Setting a crafted x-accel-mapping header. 3. Requesting a path that qualifies for proxy-based acceleration. Impact Attackers could bypass proxy-enforced restrictions and access internal endpoints intended to be…

Published by the source

10 Oct 2025, 17:31 UTC

Last modified by the source

13 Oct 2025, 15:45 UTC

Source last checked

26 Oct 2026, 15:51 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-r657-rxjc-j557

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# Patch Next advisory brief: CVE-2025-61780

Advisory: Rack has a Possible Information Disclosure Vulnerability
IDs: CVE-2025-61780, GHSA-r657-rxjc-j557
Record: https://patchnext.com/advisories/cve-2025-61780 (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 5.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: rack 3.2.3, 3.1.18, 2.2.20. A vendor fix does not mean a deployment is fixed.

## Affected components
- RubyGems rack: affected < 2.2.20; >= 3.0, < 3.1.18; >= 3.2, < 3.2.3; fixed in 3.1.18, 3.2.3, 2.2.20

## 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-r657-rxjc-j557 (GitHub-reviewed advisory GHSA-r657-rxjc-j557 lists affected ranges: RubyGems rack >=0 =3.0 =3.2 <3.2.3)

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