CVE-2025-61921

7.5 HIGH
Published: October 10, 2025 Modified: October 31, 2025

Description

Sinatra is a domain-specific language for creating web applications in Ruby. In versions prior to 4.2.0, there is a denial of service vulnerability in the `If-Match` and `If-None-Match` header parsing component of Sinatra, if the `etag` method is used when constructing the response. Carefully crafted input can cause `If-Match` and `If-None-Match` header parsing in Sinatra to take an unexpected amount of time, possibly resulting in a denial of service attack vector. This header is typically involved in generating the `ETag` header value. Any applications that use the `etag` method when generating a response are impacted. Version 4.2.0 fixes the issue.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://bugs.ruby-lang.org/issues/19104
Source: security-advisories@github.com
Issue Tracking
https://github.com/sinatra/sinatra/issues/2120
Source: security-advisories@github.com
Issue Tracking
https://github.com/sinatra/sinatra/pull/1823
Source: security-advisories@github.com
Exploit Patch
https://github.com/sinatra/sinatra/pull/2121
Source: security-advisories@github.com
Patch
https://github.com/sinatra/sinatra/security/advisories/GHSA-mr3q-g2mv-mr4q
Source: security-advisories@github.com
Vendor Advisory

5 reference(s) from NVD

Quick Stats

CVSS v3 Score
7.5 / 10.0
EPSS (Exploit Probability)
0.1%
30th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

sinatrarb