PT-2025-41597 · Sinatra+1 · Sinatra+1

Ooooooo-Q · CVE-2025-61921 · Published 2025-10-08 · Updated 2026-07-29

Positive Technologies (AI Summary)

CVSS v2.0

7.8

High

Base vector

AV:N/AC:L/Au:N/C:N/I:N/A:C

Name of the Vulnerable Software and Affected Versions Sinatra versions prior to 4.2.0

Description Sinatra, a domain-specific language for creating web applications in Ruby, contains an issue where carefully crafted input can cause excessive processing time during the parsing of If-Match and If-None-Match headers. This occurs when the etag method is used to construct responses, potentially leading to a denial of service. The If-Match and If-None-Match headers are typically used in generating the ETag header value.

Recommendations Update to Sinatra version 4.2.0 or later.

Exploit

Fix

DoS

Resource Exhaustion

Weakness Enumeration

CWE-1333

CWE-400

Related Identifiers

BDU:2026-02917

CVE-2025-61921

GHSA-MR3Q-G2MV-MR4Q

USN-8624-1

Affected Products

Debian

Sinatra

References · 34

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/61xxx/CVE-2025-61921.json · Exploit
• 🔥 https://github.com/rubysec/ruby-advisory-db/blob/master/gems/sinatra/CVE-2025-61921.yml · Exploit
• https://github.com/sinatra/sinatra/pull/2121 · Patch
• https://github.com/sinatra/sinatra/security/advisories/GHSA-mr3q-g2mv-mr4q · Vendor Advisory
• https://github.com/sinatra/sinatra/pull/1823 · Patch
• https://osv.dev/vulnerability/CVE-2025-61921 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2025-61921 · Vendor Advisory
• https://bdu.fstec.ru/vul/2026-02917 · Security Note
• https://osv.dev/vulnerability/GHSA-mr3q-g2mv-mr4q · Vendor Advisory
• https://wiki.astralinux.ru/astra-linux-se17-bulletin-2026-0421SE17 · Vendor Advisory
• https://wiki.astralinux.ru/astra-linux-se38-bulletin-2026-0305SE38 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2025-61921 · Vendor Advisory
• https://osv.dev/vulnerability/USN-8624-1 · Vendor Advisory
• https://osv.dev/vulnerability/UBUNTU-CVE-2025-61921 · Vendor Advisory
• https://wiki.astralinux.ru/x/ziLoD · Vendor Advisory