FKIE_CVE-2026-91123

Vulnerability from fkie_nvd - Published: 2026-09-24 17:17 - Updated: 2026-09-24 18:19
Severity
7.2 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Summary
Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, the iframe src traversal guard did not treat literal backslashes as path separators after decoded dot segments. A crafted source could therefore pass an allowed_iframes subpath check while browser URL normalization moved the iframe outside the intended allowed path. The resulting iframe could load content from a location that the administrator did not allow. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0.
References
security-advisories@github.comhttps://github.com/discourse/discourse/commit/042d7b159beda4f74d23e245e8b2e396d9ff8318
security-advisories@github.comhttps://github.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24
security-advisories@github.comhttps://github.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94be
security-advisories@github.comhttps://github.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579
security-advisories@github.comhttps://github.com/discourse/discourse/pull/42882
security-advisories@github.comhttps://github.com/discourse/discourse/security/advisories/GHSA-6pwj-wgg8-4rjc
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "discourse",
          "vendor": "discourse",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2026.8.0"
            },
            {
              "status": "affected",
              "version": "\u003e= 2026.7.0-latest, \u003c 2026.7.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 2026.6.0-latest, \u003c 2026.6.3"
            },
            {
              "status": "affected",
              "version": "\u003e= 2026.1.0-latest, \u003c 2026.1.8"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, the iframe src traversal guard did not treat literal backslashes as path separators after decoded dot segments. A crafted source could therefore pass an allowed_iframes subpath check while browser URL normalization moved the iframe outside the intended allowed path. The resulting iframe could load content from a location that the administrator did not allow. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0."
    }
  ],
  "id": "CVE-2026-91123",
  "lastModified": "2026-09-24T18:19:06.883",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 7.2,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 2.7,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-91123",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-24T17:11:25.606443Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-24T17:17:08.560",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/discourse/discourse/commit/042d7b159beda4f74d23e245e8b2e396d9ff8318"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94be"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/discourse/discourse/pull/42882"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/discourse/discourse/security/advisories/GHSA-6pwj-wgg8-4rjc"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-22"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}



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