GHSA-V6RJ-XM57-3P59

Vulnerability from github – Published: 2026-11-12 23:41 – Updated: 2026-11-12 23:41
VLAI
Summary
Action View: Possible XSS vulnerability in highlight helper
Details

Impact

ActionView::Helpers::TextHelper#highlight substitutes each matched phrase into the :highlighter string without escaping it and returns the result marked HTML-safe. Because sanitizing leaves quote characters in text unescaped, a match substituted into a quoted attribute value of the highlighter, such as the <a href="search?q=\1"> form shown in the method's documentation, could end the attribute value and add attributes to the element, possibly leading to XSS. Applications are affected when they pass a :highlighter that places a placeholder inside an attribute value and highlight text or phrases that a user controls. The default <mark>\1</mark> highlighter and the block form are not affected.

Details

The fixed releases HTML-escape each group substituted into the :highlighter string, so quotes in a match are rendered as &quot; and &#39;. Only the numbered placeholders \0 to \9 are expanded; other String#sub replacement escapes, such as \k<name>, \& and \\, are left as written. A match can no longer begin on the > that closes a preceding tag. Escaping makes a placeholder safe as element content or inside a quoted attribute value, but not in an unquoted attribute value, a URL, JavaScript or CSS context, or an attribute whose value is HTML. See the Action View CHANGELOG for details.

Workarounds

Use a :highlighter that places the matched phrase only in element content, such as the default <mark>\1</mark>.

Releases

The fixed releases are available at the normal locations.

Patches for those who cannot upgrade at once: - 8.1: https://github.com/rails/rails/commit/06938194b4fd59e1d2c8ab4a781f3c1e2b763425.patch - 8.0: https://github.com/rails/rails/commit/c796f6198837479ada13290eb8fa767b5219a58a.patch

Credit

This issue was found by the Anthropic OSS Scanner (ANT-2026-THHUJQVO).

Severity
6.1 (Medium)
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "actionview"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.1.0.beta1"
            },
            {
              "fixed": "8.1.4.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "actionview"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8.0.5.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-126078"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-11-12T23:41:50Z",
    "nvd_published_at": "2026-11-10T21:19:26Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n`ActionView::Helpers::TextHelper#highlight` substitutes each matched phrase into the `:highlighter` string without escaping it and returns the result marked HTML-safe. Because sanitizing leaves quote characters in text unescaped, a match substituted into a quoted attribute value of the highlighter, such as the `\u003ca href=\"search?q=\\1\"\u003e` form shown in the method\u0027s documentation, could end the attribute value and add attributes to the element, possibly leading to XSS. Applications are affected when they pass a `:highlighter` that places a placeholder inside an attribute value and highlight text or phrases that a user controls. The default `\u003cmark\u003e\\1\u003c/mark\u003e` highlighter and the block form are not affected.\n\n### Details\nThe fixed releases HTML-escape each group substituted into the `:highlighter` string, so quotes in a match are rendered as `\u0026quot;` and `\u0026#39;`. Only the numbered placeholders `\\0` to `\\9` are expanded; other `String#sub` replacement escapes, such as `\\k\u003cname\u003e`, `\\\u0026` and `\\\\`, are left as written. A match can no longer begin on the `\u003e` that closes a preceding tag. Escaping makes a placeholder safe as element content or inside a quoted attribute value, but not in an unquoted attribute value, a URL, JavaScript or CSS context, or an attribute whose value is HTML. See the Action View CHANGELOG for details.\n\n### Workarounds\nUse a `:highlighter` that places the matched phrase only in element content, such as the default `\u003cmark\u003e\\1\u003c/mark\u003e`.\n\n### Releases\nThe fixed releases are available at the normal locations.\n\nPatches for those who cannot upgrade at once:\n- 8.1: https://github.com/rails/rails/commit/06938194b4fd59e1d2c8ab4a781f3c1e2b763425.patch\n- 8.0: https://github.com/rails/rails/commit/c796f6198837479ada13290eb8fa767b5219a58a.patch\n\n### Credit\nThis issue was found by the Anthropic OSS Scanner (ANT-2026-THHUJQVO).",
  "id": "GHSA-v6rj-xm57-3p59",
  "modified": "2026-11-12T23:41:50Z",
  "published": "2026-11-12T23:41:50Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/security/advisories/GHSA-v6rj-xm57-3p59"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-126078"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/commit/06938194b4fd59e1d2c8ab4a781f3c1e2b763425"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/commit/c796f6198837479ada13290eb8fa767b5219a58a"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/rails/rails"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/releases/tag/v8.0.5.2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/releases/tag/v8.1.4.1"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/actionview/GHSA-v6rj-xm57-3p59.yml"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Action View: Possible XSS vulnerability in highlight helper"
}



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