{"id":"CVE-2026-50721","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-50721","generatedAt":"2026-10-28T02:17:40.088Z","title":"A remote attacker can use a variation on the Bleichenbacher attack to forge the SIG payload when small public exponents are being used (e.g., e=3), which could lead to impersonation.","description":"Libreswan, via the function RSA_authenticate_hash_signature_raw_rsa(), did not correctly verify the length of the authentication hash when the SIG payload of an IKEv1 packet was encoded using PKCS #1 RSA Encryption as per RFC 2313. A remote attacker can use a variation on the Bleichenbacher attack to forge the SIG payload when small public exponents are being used (e.g., e=3), which could lead to impersonation. Additionally, a remote attacker, by encoding a shorter than expected hash in the SIG payload, could trigger an assertion leading to denial-of-service. The daemon aborts and restarts; continued exploitation causes sustained denial of service. Remote code execution is not possible. X.509 certificate verifications of remote IKE peers are not affected.","published":"2026-07-02T22:16:43.000Z","lastModified":"2026-10-25T21:10:01.000Z","status":"Analyzed","sourceIdentifier":"d42dc95b-23f1-4e06-9076-20753a0fb0df","cvss":{"version":"3.1","score":5.9,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-347","CWE-617"],"affected":["libreswan/libreswan"],"epss":{"score":0.00386,"percentile":0.32427,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.39%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://libreswan.org/security/CVE-2026-50721/","tags":["Vendor Advisory"],"source":"d42dc95b-23f1-4e06-9076-20753a0fb0df"},{"url":"https://libreswan.org/security/CVE-2026-50721/CVE-2026-50721.txt","tags":["Vendor Advisory"],"source":"d42dc95b-23f1-4e06-9076-20753a0fb0df"},{"url":"https://libreswan.org/security/CVE-2026-50722/CVE-2026-50722.txt","tags":["Vendor Advisory"],"source":"d42dc95b-23f1-4e06-9076-20753a0fb0df"},{"url":"https://www.rfc-editor.org/rfc/rfc2313","tags":["Technical Description"],"source":"d42dc95b-23f1-4e06-9076-20753a0fb0df"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-50721","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}