CVE-2026-27468

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-27468", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-02-19T17:25:31.101Z", "datePublished": "2026-02-24T17:12:40.349Z", "dateUpdated": "2026-02-27T20:50:52.856Z"}, "containers": {"cna": {"title": "Mastodon may allow unconfirmed FASP to make subscriptions", "problemTypes": [{"descriptions": [{"cweId": "CWE-862", "lang": "en", "description": "CWE-862: Missing Authorization", "type": "CWE"}]}], "metrics": [{"cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "baseScore": 4.8, "baseSeverity": "MEDIUM", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:U", "version": "4.0"}}], "references": [{"name": "https://github.com/mastodon/mastodon/security/advisories/GHSA-qgmm-vr4c-ggjg", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/mastodon/mastodon/security/advisories/GHSA-qgmm-vr4c-ggjg"}, {"name": "https://github.com/mastodon/mastodon/commit/6ba6285a73c3a8b281123814d45f534e3bcebb96", "tags": ["x_refsource_MISC"], "url": "https://github.com/mastodon/mastodon/commit/6ba6285a73c3a8b281123814d45f534e3bcebb96"}], "affected": [{"vendor": "mastodon", "product": "mastodon", "versions": [{"version": ">= 4.4.0, < 4.4.14", "status": "affected"}, {"version": ">= 4.5.0, < 4.5.7", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-02-24T17:12:40.349Z"}, "descriptions": [{"lang": "en", "value": "Mastodon is a free, open-source social network server based on ActivityPub. FASP registration requires manual approval by an administrator. In versions 4.4.0 through 4.4.13 and 4.5.0 through 4.5.6, actions performed by a FASP to subscribe to account/content lifecycle events or to backfill content did not check properly whether the FASP was actually approved. This only affects Mastodon servers that have opted in to testing the experimental FASP feature by setting the environment variable `EXPERIMENTAL_FEATURES` to a value including `fasp`. An attacker can make subscriptions and request content backfill without approval by an administrator. Done once, this leads to minor information leak of URIs that are publicly available anyway. But done several times this is a serious vector for DOS, putting pressure on the sidekiq worker responsible for the `fasp` queue. The fix is included in the 4.4.14 and 4.5.7 releases. Admins that are actively testing the experimental \"fasp\" feature should update their systems. Servers not using the experimental feature flag `fasp` are not affected."}], "source": {"advisory": "GHSA-qgmm-vr4c-ggjg", "discovery": "UNKNOWN"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-02-27T20:50:45.668446Z", "id": "CVE-2026-27468", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-02-27T20:50:52.856Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-27468", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-02-27T20:50:45.668446Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-02-27T20:50:49.804Z"}}], "cna": {"title": "Mastodon may allow unconfirmed FASP to make subscriptions", "source": {"advisory": "GHSA-qgmm-vr4c-ggjg", "discovery": "UNKNOWN"}, "metrics": [{"cvssV4_0": {"version": "4.0", "baseScore": 4.8, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:U", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "LOW"}}], "affected": [{"vendor": "mastodon", "product": "mastodon", "versions": [{"status": "affected", "version": ">= 4.4.0, < 4.4.14"}, {"status": "affected", "version": ">= 4.5.0, < 4.5.7"}]}], "references": [{"url": "https://github.com/mastodon/mastodon/security/advisories/GHSA-qgmm-vr4c-ggjg", "name": "https://github.com/mastodon/mastodon/security/advisories/GHSA-qgmm-vr4c-ggjg", "tags": ["x_refsource_CONFIRM"]}, {"url": "https://github.com/mastodon/mastodon/commit/6ba6285a73c3a8b281123814d45f534e3bcebb96", "name": "https://github.com/mastodon/mastodon/commit/6ba6285a73c3a8b281123814d45f534e3bcebb96", "tags": ["x_refsource_MISC"]}], "descriptions": [{"lang": "en", "value": "Mastodon is a free, open-source social network server based on ActivityPub. FASP registration requires manual approval by an administrator. In versions 4.4.0 through 4.4.13 and 4.5.0 through 4.5.6, actions performed by a FASP to subscribe to account/content lifecycle events or to backfill content did not check properly whether the FASP was actually approved. This only affects Mastodon servers that have opted in to testing the experimental FASP feature by setting the environment variable `EXPERIMENTAL_FEATURES` to a value including `fasp`. An attacker can make subscriptions and request content backfill without approval by an administrator. Done once, this leads to minor information leak of URIs that are publicly available anyway. But done several times this is a serious vector for DOS, putting pressure on the sidekiq worker responsible for the `fasp` queue. The fix is included in the 4.4.14 and 4.5.7 releases. Admins that are actively testing the experimental \"fasp\" feature should update their systems. Servers not using the experimental feature flag `fasp` are not affected."}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-862", "description": "CWE-862: Missing Authorization"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-02-24T17:12:40.349Z"}}}, "cveMetadata": {"cveId": "CVE-2026-27468", "state": "PUBLISHED", "dateUpdated": "2026-02-27T20:50:52.856Z", "dateReserved": "2026-02-19T17:25:31.101Z", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "datePublished": "2026-02-24T17:12:40.349Z", "assignerShortName": "GitHub_M"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"product": "mastodon", "vendor": "mastodon", "versions": [{"status": "affected", "version": ">= 4.4.0, < 4.4.14"}, {"status": "affected", "version": ">= 4.5.0, < 4.5.7"}]}], "source": "security-advisories@github.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*", "matchCriteriaId": "F8A96B12-8C08-4A0C-88A8-B7B2B7AED3BF", "versionEndExcluding": "4.4.14", "versionStartIncluding": "4.4.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*", "matchCriteriaId": "65E9009A-6D3F-4758-8EAA-6D832F06F3F6", "versionEndExcluding": "4.5.7", "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. FASP registration requires manual approval by an administrator. In versions 4.4.0 through 4.4.13 and 4.5.0 through 4.5.6, actions performed by a FASP to subscribe to account/content lifecycle events or to backfill content did not check properly whether the FASP was actually approved. This only affects Mastodon servers that have opted in to testing the experimental FASP feature by setting the environment variable `EXPERIMENTAL_FEATURES` to a value including `fasp`. An attacker can make subscriptions and request content backfill without approval by an administrator. Done once, this leads to minor information leak of URIs that are publicly available anyway. But done several times this is a serious vector for DOS, putting pressure on the sidekiq worker responsible for the `fasp` queue. The fix is included in the 4.4.14 and 4.5.7 releases. Admins that are actively testing the experimental \"fasp\" feature should update their systems. Servers not using the experimental feature flag `fasp` are not affected."}, {"lang": "es", "value": "Mastodon es un servidor de red social gratuito y de c\u00f3digo abierto basado en ActivityPub. El registro FASP requiere aprobaci\u00f3n manual por parte de un administrador. En las versiones 4.4.0 a 4.4.13 y 4.5.0 a 4.5.6, las acciones realizadas por un FASP para suscribirse a eventos del ciclo de vida de cuentas/contenido o para rellenar contenido (backfill) no verificaban correctamente si el FASP estaba realmente aprobado. Esto solo afecta a los servidores de Mastodon que han optado por probar la caracter\u00edstica experimental FASP configurando la variable de entorno 'EXPERIMENTAL_FEATURES' con un valor que incluya 'fasp'. Un atacante puede realizar suscripciones y solicitar el rellenado de contenido (backfill) sin la aprobaci\u00f3n de un administrador. Hecho una vez, esto conduce a una fuga menor de informaci\u00f3n de URIs que de todos modos est\u00e1n disponibles p\u00fablicamente. Pero hecho varias veces, esto es un vector serio para DoS, ejerciendo presi\u00f3n sobre el worker de sidekiq responsable de la cola 'fasp'. La soluci\u00f3n est\u00e1 incluida en las versiones 4.4.14 y 4.5.7. Los administradores que est\u00e1n probando activamente la caracter\u00edstica experimental 'fasp' deber\u00edan actualizar sus sistemas. Los servidores que no utilizan la bandera de caracter\u00edstica experimental 'fasp' no se ven afectados."}], "id": "CVE-2026-27468", "lastModified": "2026-06-17T10:27:12.170", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.2, "baseSeverity": "HIGH", "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:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 4.2, "source": "nvd@nist.gov", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 4.8, "baseSeverity": "MEDIUM", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "UNREPORTED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-27468", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-02-27T20:50:45.668446Z", "version": "2.0.3"}}]}, "published": "2026-02-24T18:29:33.660", "references": [{"source": "security-advisories@github.com", "tags": ["Patch"], "url": "https://github.com/mastodon/mastodon/commit/6ba6285a73c3a8b281123814d45f534e3bcebb96"}, {"source": "security-advisories@github.com", "tags": ["Patch", "Vendor Advisory"], "url": "https://github.com/mastodon/mastodon/security/advisories/GHSA-qgmm-vr4c-ggjg"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-862"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[4.4.0,4.4.14)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[4.5.0,4.5.7)"}}], "enrichment": {"confidence": 89.0, "confidence_source": "matching", "scores": [{"score": 89.0, "source": "matching"}]}, "original": {"product": "mastodon", "source": "cna", "vendor": "mastodon"}, "product": "mastodon", "vendor": "joinmastodon"}], "analysis": {"en": {"generated_at": "2026-04-16T16:22:13.059783+00:00", "value": {"mitigation_remediation": ["Patch the platform to the latest supported release (4.4.14 or 4.5.7) that contains the fix.", "Disable the experimental FASP feature if not required by removing\n' fasp' from the EXPERIMENTAL_FEATURES environment variable or uninstalling the feature.", "Monitor the sidekiq fasp queue for abnormal load patterns and consider limiting backfill requests or rate\u2011controlling the queue to prevent a denial of service attack."], "summary": {"action": "Patch Update", "impact": "Information Disclosure & Denial of Service"}, "threat_synthesis": {"affected_systems": "The affected software is Mastodon, specifically the release series 4.4.x up to 4.4.13 and 4.5.x up to 4.5.6. Only servers that have enabled the experimental FASP feature via the environment variable EXPERIMENTAL_FEATURES that includes fasp are impacted; servers that do not enable this flag are not at risk.", "description_and_impact": "Mastodon versions 4.4.0 through 4.4.13 and 4.5.0 through 4.5.6 allow unapproved freeloading active subscriptions proposals (FASP) to register and request content backfill. The failure to verify that the FASP account is fully approved leads to small but public URI leaks, and repeated calls can overload the sidekiq worker that handles the fasp queue, causing a denial of service. This weakness falls under improper authorization.", "risk_and_exploitability": "The CVSS score is 4.8, EPSS is less than 1%, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalogue. The attack vector is likely remote, as an attacker can trigger the vulnerable endpoints without local access. Because the flaw permits repeated subscription creation and content backfill without authorization, exploitation could lead to minor information disclosure and, with enough repeated requests, denial of service against the sidekiq stack. Admins using the experimental fasp flag should prioritize the patch or mitigation to reduce risk."}}}}, "created": "2026-02-25T11:35:51.957298+00:00", "updated": "2026-04-16T16:30:15.935719+00:00", "vendors": ["joinmastodon", "joinmastodon$PRODUCT$mastodon"]}