GHSA-MR3Q-G2MV-MR4Q

Vulnerability from github – Published: 2025-10-10 20:28 – Updated: 2025-10-13 15:46
VLAI
Summary
Sinatra is vulnerable to ReDoS through ETag header value generation
Details

Summary

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 and you are using Ruby < 3.2.

Details

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 if they are using Ruby below version 3.2.

Resources

  • https://github.com/sinatra/sinatra/issues/2120 (report)
  • https://github.com/sinatra/sinatra/pull/2121 (fix)
  • https://github.com/sinatra/sinatra/pull/1823 (older ReDoS vulnerability)
  • https://bugs.ruby-lang.org/issues/19104 (fix in Ruby >= 3.2)
Severity
2.7 (Low)
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
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{
  "affected": [
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "sinatra"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.2.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-61921"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1333",
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-10-10T20:28:47Z",
    "nvd_published_at": "2025-10-10T20:15:38Z",
    "severity": "LOW"
  },
  "details": "### Summary\n\nThere 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 and you are using Ruby \u003c 3.2.\n\n### Details\n\nCarefully 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 if they are using Ruby below version 3.2.\n\n### Resources\n\n* https://github.com/sinatra/sinatra/issues/2120 (report)\n* https://github.com/sinatra/sinatra/pull/2121 (fix)\n* https://github.com/sinatra/sinatra/pull/1823 (older ReDoS vulnerability)\n* https://bugs.ruby-lang.org/issues/19104 (fix in Ruby \u003e= 3.2)",
  "id": "GHSA-mr3q-g2mv-mr4q",
  "modified": "2025-10-13T15:46:28Z",
  "published": "2025-10-10T20:28:47Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/sinatra/sinatra/security/advisories/GHSA-mr3q-g2mv-mr4q"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-61921"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sinatra/sinatra/issues/2120"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sinatra/sinatra/pull/1823"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sinatra/sinatra/pull/2121"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sinatra/sinatra/commit/3fe8c38dc405586f7ad8f2ac748aa53e9c3615bd"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sinatra/sinatra/commit/8ff496bd4877520599e1479d6efead39304edceb"
    },
    {
      "type": "WEB",
      "url": "https://bugs.ruby-lang.org/issues/19104"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/sinatra/CVE-2025-61921.yml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sinatra/sinatra"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Sinatra is vulnerable to ReDoS through ETag header value generation"
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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