CVE-2025-61921
It was discovered that Sinatra did not properly handle header parsing, causing ETag generation to hang when given specific input. A remote attacker could possibly use this issue to cause a denial of service.
CSIRTS triage
- What
- A vulnerability in header parsing can cause ETag generation to hang, leading to a denial of service.
- Who is affected
- All deployments of Sinatra are potentially affected by this issue.
- Urgency
- Remediation is necessary to prevent potential denial of service attacks.
- Action
- Update to the latest version of Sinatra to resolve this vulnerability.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.46% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 37% of all EPSS-scored CVEs.
Advisory coverage (1)
- unknownUSN-8624-1: Sinatra vulnerabilityubuntu · 2026-07-29
External references
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[](https://www.csirts.com/cve/CVE-2025-61921)