FKIE_CVE-2026-23961

Vulnerability from fkie_nvd - Published: 2026-01-22 02:15 - Updated: 2026-02-02 20:29
Severity ?
5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Summary
Mastodon is a free, open-source social network server based on ActivityPub. Mastodon allows server administrators to suspend remote users to prevent interactions. However, some logic errors allow already-known posts from such suspended users to appear in timelines if boosted. Furthermore, under certain circumstances, previously-unknown posts from suspended users can be processed. This issue allows old posts from suspended users to occasionally end up on timelines on all Mastodon versions. Additionally, on Mastodon versions from v4.5.0 to v4.5.4, v4.4.5 to v4.4.11, v4.3.13 to v4.3.17, and v4.2.26 to v4.2.29, remote suspended users can partially bypass the suspension to get new posts in. Mastodon versions v4.5.5, v4.4.12, v4.3.18 are patched.
References
security-advisories@github.comhttps://github.com/mastodon/mastodon/releases/tag/v4.3.18Release Notes
security-advisories@github.comhttps://github.com/mastodon/mastodon/releases/tag/v4.4.12Release Notes
security-advisories@github.comhttps://github.com/mastodon/mastodon/releases/tag/v4.5.5Release Notes
security-advisories@github.comhttps://github.com/mastodon/mastodon/security/advisories/GHSA-5h2f-wg8j-xqwpVendor Advisory
Impacted products
Vendor Product Version
joinmastodon mastodon *
joinmastodon mastodon *
joinmastodon mastodon *
To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "0ADDA491-E534-4DFB-856F-9D07F38F3A92",
              "versionEndExcluding": "4.3.18",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "9BAA2A25-EE70-4B9F-8848-2CCE9C243077",
              "versionEndExcluding": "4.4.12",
              "versionStartIncluding": "4.4.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "71845808-53CF-46D1-9A12-F14F1BAED488",
              "versionEndExcluding": "4.5.5",
              "versionStartIncluding": "4.5.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Mastodon is a free, open-source social network server based on ActivityPub. Mastodon allows server administrators to suspend remote users to prevent interactions. However, some logic errors allow already-known posts from such suspended users to appear in timelines if boosted. Furthermore, under certain circumstances, previously-unknown posts from suspended users can be processed. This issue allows old posts from suspended users to occasionally end up on timelines on all Mastodon versions. Additionally, on Mastodon versions from v4.5.0 to v4.5.4, v4.4.5 to v4.4.11, v4.3.13 to v4.3.17, and v4.2.26 to v4.2.29, remote suspended users can partially bypass the suspension to get new posts in. Mastodon versions v4.5.5, v4.4.12, v4.3.18 are patched."
    },
    {
      "lang": "es",
      "value": "Mastodon es un servidor de red social gratuito y de c\u00f3digo abierto basado en ActivityPub. Mastodon permite a los administradores de servidor suspender usuarios remotos para evitar interacciones. Sin embargo, algunos errores de l\u00f3gica permiten que haya publicaciones ya conocidas de dichos usuarios suspendidos que aparezcan en las l\u00edneas de tiempo si se promocionan. Adem\u00e1s, bajo ciertas circunstancias, se pueden procesar publicaciones previamente desconocidas de usuarios suspendidos. Este problema permite que haya publicaciones antiguas de usuarios suspendidos que, ocasionalmente, terminen en las l\u00edneas de tiempo en todas las versiones de Mastodon. Adicionalmente, en las versiones de Mastodon desde la v4.5.0 hasta la v4.5.4, de la v4.4.5 hasta la v4.4.11, de la v4.3.13 hasta la v4.3.17, y de la v4.2.26 hasta la v4.2.29, los usuarios remotos suspendidos pueden evitar parcialmente la suspensi\u00f3n para introducir nuevas publicaciones. Las versiones de Mastodon v4.5.5, v4.4.12, v4.3.18 est\u00e1n parcheadas."
    }
  ],
  "id": "CVE-2026-23961",
  "lastModified": "2026-02-02T20:29:07.753",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-01-22T02:15:52.780",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Release Notes"
      ],
      "url": "https://github.com/mastodon/mastodon/releases/tag/v4.3.18"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Release Notes"
      ],
      "url": "https://github.com/mastodon/mastodon/releases/tag/v4.4.12"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Release Notes"
      ],
      "url": "https://github.com/mastodon/mastodon/releases/tag/v4.5.5"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://github.com/mastodon/mastodon/security/advisories/GHSA-5h2f-wg8j-xqwp"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-863"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}


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Sightings

Author Source Type Date

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.