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{"bugzilla": {"description": "nebula: Nebula: Blocklist evasion via ECDSA Signature Malleability", "id": "2437914", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2437914"}, "csaw": false, "cvss3": {"cvss3_base_score": "8.1", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N", "status": "draft"}, "cwe": "CWE-347", "details": ["Nebula is a scalable overlay networking tool. In versions from 1.7.0 to 1.10.2, when using P256 certificates (which is not the default configuration), it is possible to evade a blocklist entry created against the fingerprint of a certificate by using ECDSA Signature Malleability to use a copy of the certificate with a different fingerprint. This issue has been patched in version 1.10.3."], "mitigation": {"lang": "en:us", "value": "Avoid configuring Nebula to use P256 certificates. This vulnerability is only exploitable when P256 certificates are explicitly enabled, as they are not the default configuration. Ensure Nebula deployments utilize default or other non-P256 certificate types to prevent blocklist evasion."}, "name": "CVE-2026-25793", "public_date": "2026-02-06T22:55:36Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-25793\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-25793\nhttps://github.com/slackhq/nebula/commit/f573e8a26695278f9d71587390fbfe0d0933aa21\nhttps://github.com/slackhq/nebula/security/advisories/GHSA-69x3-g4r3-p962"], "statement": "While the flaw is rated as Important, please keep in mind that there are several preconditions that must be true for a customer to be impacted:\n1. They must be used CURVE_P256 certificates (which are not the default).\n2. They must have one or more entries on their blocklist.\n3. The certificates of those blocklisted entries must be signed by a trusted CA and not expired.\n4. An attacker must have a copy of the private key and corresponding certificate for one of those blocklist entries.", "threat_severity": "Important"}