CVE-2025-61921

unknown

Published 2025-10-10 · Modified 2026-02-04

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CVSS v3

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CVSS v4 NEW

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not yet in upstream

VIR risk

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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.

Predictions

Exploit likelihood

20%

Patch ETA

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Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

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OS impact

Debian Mixed 5 releases

Version	Status	Fixed in
trixie	Affected	—
sid	Fixed	`4.2.1-1`
forky	Fixed	`4.2.1-1`
bullseye	Affected	—
bookworm	Fixed	`3.0.5-3+deb12u1`

Package impact

Ecosystem	Package	Vulnerable	Fixed
RubyGems	sinatra	`<>= 4.2.0`	`>= 4.2.0`
RubyGems	sinatra	`<4.2.0`	`4.2.0`

References

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.