GHSA-65CV-R6X7-79HV

Vulnerability from github – Published: 2020-03-19 17:30 – Updated: 2023-02-03 20:47
VLAI?
Summary
Cross site scripting vulnerability in ActionView
Details

There is a possible cross site scripting (XSS) vulnerability in ActionView's JavaScript literal escape helpers. Views that use the j or escape_javascript methods may be susceptible to XSS attacks.

Impact

There is a possible XSS vulnerability in the j and escape_javascript methods in ActionView. These methods are used for escaping JavaScript string literals. Impacted code will look something like this:

<script>let a = `<%= j unknown_input %>`</script>

or

<script>let a = `<%= escape_javascript unknown_input %>`</script>

Releases

The 6.0.2.2 and 5.2.4.2 releases are available at the normal locations.

Workarounds

For those that can't upgrade, the following monkey patch may be used:

ActionView::Helpers::JavaScriptHelper::JS_ESCAPE_MAP.merge!(
  {
    "`" => "\\`",
    "$" => "\\$"
  }
)

module ActionView::Helpers::JavaScriptHelper
  alias :old_ej :escape_javascript
  alias :old_j :j

  def escape_javascript(javascript)
    javascript = javascript.to_s
    if javascript.empty?
      result = ""
    else
      result = javascript.gsub(/(\\|<\/|\r\n|\342\200\250|\342\200\251|[\n\r"']|[`]|[$])/u, JS_ESCAPE_MAP)
    end
    javascript.html_safe? ? result.html_safe : result
  end

  alias :j :escape_javascript
end

Patches

To aid users who aren't able to upgrade immediately we have provided patches for the two supported release series. They are in git-am format and consist of a single changeset.

Please note that only the 5.2 and 6.0 series are supported at present. Users of earlier unsupported releases are advised to upgrade as soon as possible as we cannot guarantee the continued availability of security fixes for unsupported releases.

Credits

Thanks to Jesse Campos from Chef Secure

Severity ?
4.8 (Medium)
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.2.4.1"
      },
      "package": {
        "ecosystem": "RubyGems",
        "name": "actionview"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.2.4.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 6.0.2.1"
      },
      "package": {
        "ecosystem": "RubyGems",
        "name": "actionview"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.0.0"
            },
            {
              "fixed": "6.0.2.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2020-5267"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-80"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2020-03-19T17:29:40Z",
    "nvd_published_at": "2020-03-19T18:15:00Z",
    "severity": "MODERATE"
  },
  "details": "There is a possible cross site scripting (XSS) vulnerability in ActionView\u0027s JavaScript literal escape helpers.  Views that use the `j` or `escape_javascript` methods may be susceptible to XSS attacks.\n\n### Impact\n\nThere is a possible XSS vulnerability in the `j` and `escape_javascript` methods in ActionView.  These methods are used for escaping JavaScript string literals.  Impacted code will look something like this:\n\n```erb\n\u003cscript\u003elet a = `\u003c%= j unknown_input %\u003e`\u003c/script\u003e\n```\n\nor\n\n```erb\n\u003cscript\u003elet a = `\u003c%= escape_javascript unknown_input %\u003e`\u003c/script\u003e\n```\n\n### Releases\n\nThe 6.0.2.2 and 5.2.4.2 releases are available at the normal locations.\n\n### Workarounds\n\nFor those that can\u0027t upgrade, the following monkey patch may be used:\n\n```ruby\nActionView::Helpers::JavaScriptHelper::JS_ESCAPE_MAP.merge!(\n  {\n    \"`\" =\u003e \"\\\\`\",\n    \"$\" =\u003e \"\\\\$\"\n  }\n)\n\nmodule ActionView::Helpers::JavaScriptHelper\n  alias :old_ej :escape_javascript\n  alias :old_j :j\n\n  def escape_javascript(javascript)\n    javascript = javascript.to_s\n    if javascript.empty?\n      result = \"\"\n    else\n      result = javascript.gsub(/(\\\\|\u003c\\/|\\r\\n|\\342\\200\\250|\\342\\200\\251|[\\n\\r\"\u0027]|[`]|[$])/u, JS_ESCAPE_MAP)\n    end\n    javascript.html_safe? ? result.html_safe : result\n  end\n\n  alias :j :escape_javascript\nend\n```\n\n### Patches\n\nTo aid users who aren\u0027t able to upgrade immediately we have provided patches for\nthe two supported release series. They are in git-am format and consist of a\nsingle changeset.\n\n* [5-2-js-helper-xss.patch](https://gist.github.com/tenderlove/c042ff49f0347c37e99183a6502accc6#file-5-2-js-helper-xss-patch) - Patch for 5.2 series\n* [6-0-js-helper-xss.patch](https://gist.github.com/tenderlove/c042ff49f0347c37e99183a6502accc6#file-6-0-js-helper-xss-patch) - Patch for 6.0 series\n\nPlease note that only the 5.2 and 6.0 series are supported at present. Users\nof earlier unsupported releases are advised to upgrade as soon as possible as we\ncannot guarantee the continued availability of security fixes for unsupported\nreleases.\n\n### Credits\n\nThanks to Jesse Campos from Chef Secure",
  "id": "GHSA-65cv-r6x7-79hv",
  "modified": "2023-02-03T20:47:05Z",
  "published": "2020-03-19T17:30:29Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/security/advisories/GHSA-65cv-r6x7-79hv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-5267"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rails/rails/commit/033a738817abd6e446e1b320cb7d1a5c15224e9a"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/actionview/CVE-2020-5267.yml"
    },
    {
      "type": "WEB",
      "url": "https://groups.google.com/forum/#!topic/rubyonrails-security/55reWMM_Pg8"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2020/03/msg00022.html"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/XJ7NUWXAEVRQCROIIBV4C6WXO6IR3KSB"
    },
    {
      "type": "WEB",
      "url": "http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00019.html"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2020/03/19/1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Cross site scripting vulnerability in ActionView"
}


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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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