Bug 2403178 (CVE-2025-61921)

Summary: CVE-2025-61921 sinatra: Sinatra has ReDoS vulnerability in ETag header value generation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akostadi, amasferr, cbartlet, dmayorov, jlledo, mmakovy, pantinor, tjochec, tsedmik
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Sinatra. A Regular Expression Denial of Service (ReDoS) vulnerability can be triggered when parsing the If-Match and If-None-Match HTTP headers. A remote attacker can exploit this issue by sending a specially crafted header to an application endpoint that uses the etag method, causing a excessive CPU consumption and potentially resulting in a denial of service.
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Description OSIDB Bzimport 2025-10-10 20:01:32 UTC 
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.