FKIE_CVE-2026-50721

Vulnerability from fkie_nvd - Published: 2026-07-02 22:16 - Updated: 2026-07-09 15:46
Severity ?
8.1 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
5.9 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
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.
References
d42dc95b-23f1-4e06-9076-20753a0fb0dfhttps://libreswan.org/security/CVE-2026-50721/Vendor Advisory
d42dc95b-23f1-4e06-9076-20753a0fb0dfhttps://libreswan.org/security/CVE-2026-50721/CVE-2026-50721.txtVendor Advisory
d42dc95b-23f1-4e06-9076-20753a0fb0dfhttps://libreswan.org/security/CVE-2026-50722/CVE-2026-50722.txtVendor Advisory
d42dc95b-23f1-4e06-9076-20753a0fb0dfhttps://www.rfc-editor.org/rfc/rfc2313Technical Description
Impacted products
Vendor Product Version
libreswan libreswan *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://github.com/libreswan/libreswan",
          "defaultStatus": "unaffected",
          "packageName": "libreswan",
          "product": "libreswan",
          "programRoutines": [
            {
              "name": "RSA_authenticate_hash_signature_raw_rsa"
            }
          ],
          "repo": "https://github.com/libreswan/libreswan",
          "vendor": "The Libreswan Project",
          "versions": [
            {
              "lessThanOrEqual": "5.3",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.3.1",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "d42dc95b-23f1-4e06-9076-20753a0fb0df"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:libreswan:libreswan:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "0D5C4D8F-3003-4ACA-A065-E03AEE680115",
              "versionEndExcluding": "5.3.1",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    }
  ],
  "id": "CVE-2026-50721",
  "lastModified": "2026-07-09T15:46:40.770",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 5.9,
        "source": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 5.9,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-50721",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-07-06T18:12:17.199605Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-02T22:16:43.367",
  "references": [
    {
      "source": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://libreswan.org/security/CVE-2026-50721/"
    },
    {
      "source": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://libreswan.org/security/CVE-2026-50721/CVE-2026-50721.txt"
    },
    {
      "source": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://libreswan.org/security/CVE-2026-50722/CVE-2026-50722.txt"
    },
    {
      "source": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
      "tags": [
        "Technical Description"
      ],
      "url": "https://www.rfc-editor.org/rfc/rfc2313"
    }
  ],
  "sourceIdentifier": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-347"
        },
        {
          "lang": "en",
          "value": "CWE-617"
        }
      ],
      "source": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
      "type": "Secondary"
    }
  ]
}


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