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CVE-2025-61921— Sinatra has ReDoS vulnerability in ETag header value generation

Quick assessment

Affected
sinatra sinatra
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Sinatra是Sinatra开源的一个DSL，用于以最少的努力快速创建Ruby中的web应用程序 Sinatra 4.2.0之前版本存在安全漏洞，该漏洞源于If-Match和If-None-Match标头解析组件存在缺陷，可能导致拒绝服务攻击。

AI Predicted 7.5 Difficulty: Easy EPSS 0.50% · P41

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2025-61921

Vulnerability Information
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Vulnerability Title
Sinatra has ReDoS vulnerability in ETag header value generation
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
Source: CVE Program / CVE List V5
Vulnerability Type
CWE-1333
Source: CVE Program / CVE List V5
Vulnerability Title
Sinatra 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Sinatra是Sinatra开源的一个DSL，用于以最少的努力快速创建Ruby中的web应用程序 Sinatra 4.2.0之前版本存在安全漏洞，该漏洞源于If-Match和If-None-Match标头解析组件存在缺陷，可能导致拒绝服务攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
sinatra sinatra < 4.2.0 -

II. Public POCs for CVE-2025-61921

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III. Intelligence Information for CVE-2025-61921

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IV. Related Vulnerabilities

Same product: sinatra
Same vendor: sinatra
Same weakness: CWE-1333

V. Comments for CVE-2025-61921

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