CVE-2026-72722 (GCVE-0-2026-72722)

Vulnerability from cvelistv5 – Published: 2026-08-10 15:54 – Updated: 2026-08-10 15:54
VLAI
Title
Discourse: Duplicate lookup reveals restricted topic titles through canonicalized URLs
Summary
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, TopicLink.extract_from, TopicLink.ensure_entry_for, and TopicLink.duplicate_lookup do not consistently enforce Guardian.can_see? checks when processing internal links. An authenticated user can submit links to restricted topics, private messages, or hidden posts and receive canonicalized slugs or titles in the composer_messages duplicate_lookup response even though the targets are not visible to that user. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.
Severity
4.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
CWE
Assigner
References
Impacted products
Vendor Product Version
discourse discourse Affected: < 2026.1.6
Affected: >= 2026.5.0-latest, < 2026.5.2
Affected: >= 2026.6.0-latest, < 2026.6.1
Affected: >= 2026.7.0-latest, < 2026.7.0
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "discourse",
          "vendor": "discourse",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2026.1.6"
            },
            {
              "status": "affected",
              "version": "\u003e= 2026.5.0-latest, \u003c 2026.5.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 2026.6.0-latest, \u003c 2026.6.1"
            },
            {
              "status": "affected",
              "version": "\u003e= 2026.7.0-latest, \u003c 2026.7.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, TopicLink.extract_from, TopicLink.ensure_entry_for, and TopicLink.duplicate_lookup do not consistently enforce Guardian.can_see? checks when processing internal links. An authenticated user can submit links to restricted topics, private messages, or hidden posts and receive canonicalized slugs or titles in the composer_messages duplicate_lookup response even though the targets are not visible to that user. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 4.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-862",
              "description": "CWE-862: Missing Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-10T15:54:35.907Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/discourse/discourse/security/advisories/GHSA-4fx9-5m29-83p4",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/discourse/discourse/security/advisories/GHSA-4fx9-5m29-83p4"
        },
        {
          "name": "https://github.com/discourse/discourse/pull/42091",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/pull/42091"
        },
        {
          "name": "https://github.com/discourse/discourse/pull/42092",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/pull/42092"
        },
        {
          "name": "https://github.com/discourse/discourse/pull/42093",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/pull/42093"
        },
        {
          "name": "https://github.com/discourse/discourse/pull/42094",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/pull/42094"
        },
        {
          "name": "https://github.com/discourse/discourse/commit/45abd925e46e8be40d2d047bced26628f26e4e31",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/commit/45abd925e46e8be40d2d047bced26628f26e4e31"
        },
        {
          "name": "https://github.com/discourse/discourse/commit/7d7ce546ac86e24a6512b321ace69fc52fe37bf4",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/commit/7d7ce546ac86e24a6512b321ace69fc52fe37bf4"
        },
        {
          "name": "https://github.com/discourse/discourse/commit/836a251d54a1004fb1c463a7d299b933b176191f",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/commit/836a251d54a1004fb1c463a7d299b933b176191f"
        },
        {
          "name": "https://github.com/discourse/discourse/commit/e54ba27eacee0f14f315e510e287e7ac2e4bdb1a",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/commit/e54ba27eacee0f14f315e510e287e7ac2e4bdb1a"
        }
      ],
      "source": {
        "advisory": "GHSA-4fx9-5m29-83p4",
        "discovery": "UNKNOWN"
      },
      "title": "Discourse: Duplicate lookup reveals restricted topic titles through canonicalized URLs"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-72722",
    "datePublished": "2026-08-10T15:54:35.907Z",
    "dateReserved": "2026-08-10T13:48:09.545Z",
    "dateUpdated": "2026-08-10T15:54:35.907Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-72722\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-08-10T16:19:49.520\",\"lastModified\":\"2026-08-10T16:19:49.520\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, TopicLink.extract_from, TopicLink.ensure_entry_for, and TopicLink.duplicate_lookup do not consistently enforce Guardian.can_see? checks when processing internal links. An authenticated user can submit links to restricted topics, private messages, or hidden posts and receive canonicalized slugs or titles in the composer_messages duplicate_lookup response even though the targets are not visible to that user. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"discourse\",\"product\":\"discourse\",\"versions\":[{\"version\":\"\u003c 2026.1.6\",\"status\":\"affected\"},{\"version\":\"\u003e= 2026.5.0-latest, \u003c 2026.5.2\",\"status\":\"affected\"},{\"version\":\"\u003e= 2026.6.0-latest, \u003c 2026.6.1\",\"status\":\"affected\"},{\"version\":\"\u003e= 2026.7.0-latest, \u003c 2026.7.0\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N\",\"baseScore\":4.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"LOW\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":2.8,\"impactScore\":1.4}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-862\"}]}],\"references\":[{\"url\":\"https://github.com/discourse/discourse/commit/45abd925e46e8be40d2d047bced26628f26e4e31\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/commit/7d7ce546ac86e24a6512b321ace69fc52fe37bf4\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/commit/836a251d54a1004fb1c463a7d299b933b176191f\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/commit/e54ba27eacee0f14f315e510e287e7ac2e4bdb1a\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/pull/42091\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/pull/42092\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/pull/42093\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/pull/42094\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/security/advisories/GHSA-4fx9-5m29-83p4\",\"source\":\"security-advisories@github.com\"}]}}"
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.