{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-50722", "assignerOrgId": "d42dc95b-23f1-4e06-9076-20753a0fb0df", "state": "PUBLISHED", "assignerShortName": "libreswan", "dateReserved": "2026-06-05T16:10:05.751Z", "datePublished": "2026-07-02T21:34:41.413Z", "dateUpdated": "2026-07-07T17:02:06.722Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "d42dc95b-23f1-4e06-9076-20753a0fb0df", "shortName": "libreswan", "dateUpdated": "2026-07-02T21:34:41.413Z"}, "title": "IKEv2 Denial of Service via RSA-SHA1 (PKCS#1 RSASSA-PKCS1-v1_5) authentication payload", "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>Libreswan, via the function RSA_authenticate_hash_signature_pkcs1_1_5_rsa(), did not correctly verify the DER encoding of the ASN.1 digest when the IKEv2 AUTH payload was encoded using RSASSA-PKCS1-v1_5 (RFC 8017). 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Additionally, a remote attacker, by encoding a shorter than expected hash in the AUTH 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. 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Authentication bypass requires weak RSA exponents (e=3) which have been disallowed by most cryptographic libraries for over a decade. DoS is mitigated by automatic daemon restart."}}}], "workarounds": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>If Windows support is not needed, configure <code>authby=ecdsa</code> or <code>authby=rsa-sha2</code> (or both via <code>authby=ecdsa,rsa-sha2</code>) to disallow the fallback of RSA PKCS#1 1.5. The <code>leftauth=</code> and <code>rightauth=</code> settings can be updated similarly if those are in use instead of <code>authby</code>.</p>"}], "value": "If Windows support is not needed, configure authby=ecdsa or authby=rsa-sha2 (or both via authby=ecdsa,rsa-sha2) to disallow the fallback of RSA PKCS#1 1.5. The leftauth= and rightauth= settings can be updated similarly if those are in use instead of authby."}], "solutions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>Upgrade to libreswan 5.3.1 or later. Patches for libreswan 4.15 and 5.3 are available at <a href=\"https://libreswan.org/security/CVE-2026-50722/\">https://libreswan.org/security/CVE-2026-50722/</a></p>"}], "value": "Upgrade to libreswan 5.3.1 or later. Patches for libreswan 4.15 and 5.3 are available at https://libreswan.org/security/CVE-2026-50722/"}], "exploits": [{"lang": "en", "value": "No known exploitation in the wild. The authentication bypass requires the target to use RSA keys with weak exponents (e=3), which have been disallowed by most cryptographic libraries for at least a decade. 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