Inefficient Regular Expression Complexity Affecting ruby-sinatra package, versions <1.4.8-1ubuntu0.1~esm3


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.46% (39th percentile)

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  • Snyk IDSNYK-UBUNTU1804-RUBYSINATRA-13569963
  • published29 Jul 2026
  • disclosed10 Oct 2025

Introduced: 10 Oct 2025

CVE-2025-61921  (opens in a new tab)
CWE-1333  (opens in a new tab)

How to fix?

Upgrade Ubuntu:18.04 ruby-sinatra to version 1.4.8-1ubuntu0.1~esm3 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream ruby-sinatra package and not the ruby-sinatra package as distributed by Ubuntu. See How to fix? for Ubuntu:18.04 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1