Vulnerability-Lookup

GHSA-89VF-4333-QX8V

Vulnerability from github – Published: 2026-03-23 20:53 – Updated: 2026-05-13 16:15

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

Show details on source website

JSON

To clipboard

{
  "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": "2026-05-13T16:15:43Z",
  "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"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/activesupport/CVE-2026-33170.yml"
    }
  ],
  "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#%"
}

CVE-2026-33170 (GCVE-0-2026-33170)

Vulnerability from cvelistv5 – Published: 2026-03-23 23:09 – Updated: 2026-03-25 19:20

Title

Rails Active Support has a possible XSS vulnerability in SafeBuffer#%

Summary

Active Support is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, `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. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.

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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-03-25 19:20 UTC

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Assigner

GitHub_M mitre root

References

7 references

URL	Tags
https://github.com/rails/rails/security/advisorie…	x_refsource_CONFIRM
https://github.com/rails/rails/commit/50d732af3b7…	x_refsource_MISC
https://github.com/rails/rails/commit/6e8a8110800…	x_refsource_MISC
https://github.com/rails/rails/commit/c1ad0e8e197…	x_refsource_MISC
https://github.com/rails/rails/releases/tag/v7.2.3.1	x_refsource_MISC
https://github.com/rails/rails/releases/tag/v8.0.4.1	x_refsource_MISC
https://github.com/rails/rails/releases/tag/v8.1.2.1	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
rails	activesupport	Affected: >= 8.1.0.beta1, < 8.1.2.1 Affected: >= 8.0.0.beta1, < 8.0.4.1 Affected: < 7.2.3.1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-33170",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-25T19:20:16.086015Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-25T19:20:28.280Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "activesupport",
          "vendor": "rails",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 8.1.0.beta1, \u003c 8.1.2.1"
            },
            {
              "status": "affected",
              "version": "\u003e= 8.0.0.beta1, \u003c 8.0.4.1"
            },
            {
              "status": "affected",
              "version": "\u003c 7.2.3.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Active Support is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, `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. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "PASSIVE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "LOW"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-79",
              "description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-23T23:19:36.467Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8v",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8v"
        },
        {
          "name": "https://github.com/rails/rails/commit/50d732af3b7c8aaf63cbcca0becbc00279b215b7",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/rails/rails/commit/50d732af3b7c8aaf63cbcca0becbc00279b215b7"
        },
        {
          "name": "https://github.com/rails/rails/commit/6e8a81108001d58043de9e54a06fca58962fc2db",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/rails/rails/commit/6e8a81108001d58043de9e54a06fca58962fc2db"
        },
        {
          "name": "https://github.com/rails/rails/commit/c1ad0e8e1972032f3395853a5e99cea035035beb",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/rails/rails/commit/c1ad0e8e1972032f3395853a5e99cea035035beb"
        },
        {
          "name": "https://github.com/rails/rails/releases/tag/v7.2.3.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/rails/rails/releases/tag/v7.2.3.1"
        },
        {
          "name": "https://github.com/rails/rails/releases/tag/v8.0.4.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/rails/rails/releases/tag/v8.0.4.1"
        },
        {
          "name": "https://github.com/rails/rails/releases/tag/v8.1.2.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/rails/rails/releases/tag/v8.1.2.1"
        }
      ],
      "source": {
        "advisory": "GHSA-89vf-4333-qx8v",
        "discovery": "UNKNOWN"
      },
      "title": "Rails Active Support has a possible XSS vulnerability in SafeBuffer#%"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-33170",
    "datePublished": "2026-03-23T23:09:48.923Z",
    "dateReserved": "2026-03-17T21:17:08.888Z",
    "dateUpdated": "2026-03-25T19:20:28.280Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

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.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.