CVE-2026-24471

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{"affected": [{"affectedData": [{"product": "continuwuity", "vendor": "continuwuity", "versions": [{"status": "affected", "version": "< 0.5.1"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "continuwuity is a Matrix homeserver written in Rust. This vulnerability allows an attacker with a malicious remote server to cause the local server to sign an arbitrary event upon user interaction. Upon a user account leaving a room (rejecting an invite), joining a room or knocking on a room, the victim server may ask a remote server for assistance. If the victim asks the attacker server for assistance the attacker is able to provide an arbitrary event, which the victim will sign and return to the attacker. For the /leave endpoint, this works for any event with a supported room version, where the origin and origin_server_ts is set by the victim. For the /join endpoint, an additionally victim-set content field in the format of a join membership is needed. For the /knock endpoint, an additional victim-set content field in the format of a knock membership and a room version not between 1 and 6 is needed. This was exploited as a part of a larger chain against the continuwuity.org homeserver. This vulnerability affects all Conduit-derived servers. This vulnerability is fixed in Continuwuity 0.5.1, Conduit 0.10.11, Grapevine 0aae932b, and Tuwunel 1.4.9."}, {"lang": "es", "value": "continuwuity es un homeserver de Matrix escrito en Rust. Esta vulnerabilidad permite a un atacante con un servidor remoto malicioso hacer que el servidor local firme un evento arbitrario tras la interacci\u00f3n del usuario. Cuando una cuenta de usuario abandona una sala (rechazando una invitaci\u00f3n), se une a una sala o llama a la puerta de una sala, el servidor v\u00edctima puede pedir asistencia a un servidor remoto. Si la v\u00edctima pide asistencia al servidor atacante, el atacante puede proporcionar un evento arbitrario, que la v\u00edctima firmar\u00e1 y devolver\u00e1 al atacante. Para el endpoint /leave, esto funciona para cualquier evento con una versi\u00f3n de sala compatible, donde el origen y origin_server_ts son establecidos por la v\u00edctima. Para el endpoint /join, se necesita un campo de contenido adicionalmente establecido por la v\u00edctima en el formato de una membres\u00eda de uni\u00f3n. Para el endpoint /knock, se necesita un campo de contenido adicional establecido por la v\u00edctima en el formato de una membres\u00eda de knock y una versi\u00f3n de sala que no est\u00e9 entre 1 y 6. Esto fue explotado como parte de una cadena m\u00e1s grande contra el homeserver continuwuity.org. Esta vulnerabilidad afecta a todos los servidores derivados de Conduit. Esta vulnerabilidad est\u00e1 corregida en Continuwuity 0.5.1, Conduit 0.10.11, Grapevine 0aae932b y Tuwunel 1.4.9."}], "id": "CVE-2026-24471", "lastModified": "2026-06-17T10:23:07.140", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 9.3, "baseSeverity": "CRITICAL", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "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": "HIGH", "subConfidentialityImpact": "LOW", "subIntegrityImpact": "LOW", "userInteraction": "PASSIVE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:L/SI:L/SA:H/E:X/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": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-24471", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-02-03T14:52:55.688879Z", "version": "2.0.3"}}]}, "published": "2026-02-02T23:16:08.270", "references": [{"source": "security-advisories@github.com", "url": "https://forgejo.ellis.link/continuwuation/continuwuity/commit/12aecf809172205436c852a1eaf268c1a2c3a900"}, {"source": "security-advisories@github.com", "url": "https://github.com/continuwuity/continuwuity/security/advisories/GHSA-m5p2-vccg-8c9v"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-441"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"analysis": {"en": {"generated_at": "2026-04-18T00:34:42.575098+00:00", "value": {"mitigation_remediation": ["Update continuwuity to version\u00a00.5.1 or later, Conduit to\u00a00.10.11, Grapevine to commit\u00a00aae932b, or Tuwunel to\u00a01.4.9", "Configure the homeserver to refuse assistance requests from unknown or untrusted remote servers by restricting the domain whitelist to trusted domains only", "Audit and enforce strict validation of all event fields received from remote servers, ensuring origin, timestamp, and membership content are locally generated or cross\u2011checked before signing"], "summary": {"action": "Apply Patch", "impact": "Unauthorized Event Signing"}, "threat_synthesis": {"affected_systems": "Vulnerable servers include all Conduit\u2011derived homeservers written in Rust, such as continuwuity, Conduit, Grapevine, and Tuwunel. Affected versions are prior to continuwuity\u00a00.5.1, Conduit\u00a00.10.11, Grapevine\u00a00aae932b, and Tuwunel\u00a01.4.9.", "description_and_impact": "This flaw allows a malicious remote server to compel a local Matrix homeserver to sign arbitrary events when a user interacts with rooms. The server blindly trusts data from the remote server, missing validation of critical fields such as origin, initiation timestamps, and membership content. As a result, an attacker can forge signed events that appear to originate from legitimate users, potentially enabling unauthorized actions such as membership manipulation or replay attacks. The weakness is a classic Confused\u2011Deputy scenario (CWE\u2011441).", "risk_and_exploitability": "The severity score of 9.3 indicates critical impact for affected deployments. Exploitability probability, as measured by EPSS, is less than 1\u2011percent, suggesting low likelihood of widespread attacks but not zero; attackers would need to run a malicious server and convince victims to join, leave, or knock on rooms. The vulnerability is not listed in CISA\u2019s Known Exploited Vulnerabilities catalog, but the high CVSS and potential loss of integrity make proactive mitigation essential."}}}}, "created": "2026-02-04T12:18:04.416148+00:00", "updated": "2026-04-18T00:45:32.234889+00:00", "vendors": ["conduit", "conduit$PRODUCT$conduit", "continuwuity", "continuwuity$PRODUCT$continuwuity"]}