CVE-2026-59828 (GCVE-0-2026-59828)

Vulnerability from cvelistv5 – Published: 2026-07-09 22:04 – Updated: 2026-07-09 22:04
VLAI
Title
Discourse: Hidden post revisions leak through adjacent visible diffs
Summary
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, post revisions that should be hidden from regular users could be leaked through visible diffs on adjacent revisions serialized by PostRevisionSerializer. This issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CWE
  • CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor
Assigner
References
Impacted products
Vendor Product Version
discourse discourse Affected: >= 2026.1.0-latest, < 2026.1.5
Affected: >= 2026.4.0-latest, < 2026.4.2
Affected: >= 2026.5.0-latest, < 2026.5.1
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "discourse",
          "vendor": "discourse",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 2026.1.0-latest, \u003c 2026.1.5"
            },
            {
              "status": "affected",
              "version": "\u003e= 2026.4.0-latest, \u003c 2026.4.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 2026.5.0-latest, \u003c 2026.5.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, post revisions that should be hidden from regular users could be leaked through visible diffs on adjacent revisions serialized by PostRevisionSerializer. This issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-200",
              "description": "CWE-200: Exposure of Sensitive Information to an Unauthorized Actor",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-09T22:04:50.777Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/discourse/discourse/security/advisories/GHSA-q456-4f8q-42vx",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/discourse/discourse/security/advisories/GHSA-q456-4f8q-42vx"
        },
        {
          "name": "https://github.com/discourse/discourse/commit/1f26c1163ce87a2abbd1d01780ab1b5fb16e75f6",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/commit/1f26c1163ce87a2abbd1d01780ab1b5fb16e75f6"
        },
        {
          "name": "https://github.com/discourse/discourse/commit/8b773332b0f937dfcd894ed56d56fc5a81578d9d",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/commit/8b773332b0f937dfcd894ed56d56fc5a81578d9d"
        },
        {
          "name": "https://github.com/discourse/discourse/commit/8d36da1b68c906592abde3f2e94d505cdf097435",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/commit/8d36da1b68c906592abde3f2e94d505cdf097435"
        },
        {
          "name": "https://github.com/discourse/discourse/commit/d58988d46bb1019bfa8b8330ae81a1a134e08511",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/commit/d58988d46bb1019bfa8b8330ae81a1a134e08511"
        },
        {
          "name": "https://github.com/discourse/discourse/releases/tag/v2026.1.5",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/releases/tag/v2026.1.5"
        },
        {
          "name": "https://github.com/discourse/discourse/releases/tag/v2026.4.2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/releases/tag/v2026.4.2"
        },
        {
          "name": "https://github.com/discourse/discourse/releases/tag/v2026.5.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/releases/tag/v2026.5.1"
        },
        {
          "name": "https://github.com/discourse/discourse/releases/tag/v2026.6.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/releases/tag/v2026.6.0"
        }
      ],
      "source": {
        "advisory": "GHSA-q456-4f8q-42vx",
        "discovery": "UNKNOWN"
      },
      "title": "Discourse: Hidden post revisions leak through adjacent visible diffs"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-59828",
    "datePublished": "2026-07-09T22:04:50.777Z",
    "dateReserved": "2026-07-07T15:00:50.979Z",
    "dateUpdated": "2026-07-09T22:04:50.777Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-59828\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-07-09T22:17:09.973\",\"lastModified\":\"2026-07-09T22:17:09.973\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, post revisions that should be hidden from regular users could be leaked through visible diffs on adjacent revisions serialized by PostRevisionSerializer. This issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"discourse\",\"product\":\"discourse\",\"versions\":[{\"version\":\"\u003e= 2026.1.0-latest, \u003c 2026.1.5\",\"status\":\"affected\"},{\"version\":\"\u003e= 2026.4.0-latest, \u003c 2026.4.2\",\"status\":\"affected\"},{\"version\":\"\u003e= 2026.5.0-latest, \u003c 2026.5.1\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N\",\"baseScore\":5.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"LOW\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":3.9,\"impactScore\":1.4}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-200\"}]}],\"references\":[{\"url\":\"https://github.com/discourse/discourse/commit/1f26c1163ce87a2abbd1d01780ab1b5fb16e75f6\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/commit/8b773332b0f937dfcd894ed56d56fc5a81578d9d\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/commit/8d36da1b68c906592abde3f2e94d505cdf097435\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/commit/d58988d46bb1019bfa8b8330ae81a1a134e08511\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/releases/tag/v2026.1.5\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/releases/tag/v2026.4.2\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/releases/tag/v2026.5.1\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/releases/tag/v2026.6.0\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/discourse/discourse/security/advisories/GHSA-q456-4f8q-42vx\",\"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.