GHSA-89VF-4333-QX8V

Vulnerability from github – Published: 2026-03-23 20:53 – Updated: 2026-04-09 19:06
VLAI?
Summary
Rails Active Support has a possible XSS vulnerability in SafeBuffer#%
Details

Impact

SafeBuffer#% does not propagate the @html_unsafe flag to the newly created buffer. If a SafeBuffer is mutated in place (e.g. via gsub!) and then formatted with % using untrusted arguments, the result incorrectly reports html_safe? == true, bypassing ERB auto-escaping and possibly leading to XSS.

Releases

The fixed releases are available at the normal locations.

Credit

This issue was responsibly reported by @ch4n3-yoon

Severity ?
5.3 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "activesupport"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.1.0.beta1"
            },
            {
              "fixed": "8.1.2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "activesupport"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.0.0.beta1"
            },
            {
              "fixed": "8.0.4.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "activesupport"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.2.3.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-33170"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-23T20:53:28Z",
    "nvd_published_at": "2026-03-24T00:16:28Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n`SafeBuffer#%` does not propagate the `@html_unsafe` flag to the newly created buffer. If a `SafeBuffer` is mutated in place (e.g. via `gsub!`) and then formatted with `%` using untrusted arguments, the result incorrectly reports `html_safe? == true`, bypassing ERB auto-escaping and possibly leading to XSS.\n\n### Releases\nThe fixed releases are available at the normal locations.\n\n### Credit\nThis issue was responsibly reported by @ch4n3-yoon",
  "id": "GHSA-89vf-4333-qx8v",
  "modified": "2026-04-09T19:06:46Z",
  "published": "2026-03-23T20:53:28Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8v"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33170"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/commit/50d732af3b7c8aaf63cbcca0becbc00279b215b7"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/commit/6e8a81108001d58043de9e54a06fca58962fc2db"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/commit/c1ad0e8e1972032f3395853a5e99cea035035beb"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/rails/rails"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/releases/tag/v7.2.3.1"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/releases/tag/v8.0.4.1"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/releases/tag/v8.1.2.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Rails Active Support has a possible XSS vulnerability in SafeBuffer#%"
}


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