Vulnerability-Lookup

FKIE_CVE-2026-77206

Vulnerability from fkie_nvd - Published: 2026-10-13 22:18 - Updated: 2026-10-16 19:55

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

Libreswan's IKEv2 state machine has a null pointer dereference bug in the EAP handling code for authentication. As a result of inconsistency within the IKEv2 state machine code, this bug can be triggered by any IKEv2 connection, even if EAP is not configured at all. The error is caused by a fall-through where it incorrectly dereferences ike->sa.st_eap which is NULL. A malicious IKE_AUTH packet can trigger this bug, meaning the peer does not need to be authenticated. The bug results in a crash and restart of the pluto daemon. No remote code execution is possible. Continued exploitation can cause a denial of service.

References

	URL	Tags
	d42dc95b-23f1-4e06-9076-20753a0fb0df	https://libreswan.org/security/CVE-2026-77206/
	d42dc95b-23f1-4e06-9076-20753a0fb0df	https://libreswan.org/security/CVE-2026-77206/CVE-2026-77206.txt

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://github.com/libreswan/libreswan",
          "defaultStatus": "unaffected",
          "packageName": "libreswan",
          "product": "libreswan",
          "repo": "https://github.com/libreswan/libreswan",
          "vendor": "The Libreswan Project",
          "versions": [
            {
              "lessThanOrEqual": "5.3.2",
              "status": "affected",
              "version": "4.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.4",
              "status": "affected",
              "version": "5.4",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.3.3",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.4.1",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "d42dc95b-23f1-4e06-9076-20753a0fb0df"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Libreswan\u0027s IKEv2 state machine has a null pointer dereference bug in the EAP handling code for authentication. As a result of inconsistency within the IKEv2 state machine code, this bug can be triggered by any IKEv2 connection, even if EAP is not configured at all. The error is caused by a fall-through where it incorrectly dereferences ike-\u003esa.st_eap which is NULL. A malicious IKE_AUTH packet can trigger this bug, meaning the peer does not need to be authenticated. The bug results in a crash and restart of the pluto daemon. No remote code execution is possible. Continued exploitation can cause a denial of service."
    }
  ],
  "id": "CVE-2026-77206",
  "lastModified": "2026-10-16T19:55:59.740",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-77206",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-16T15:14:41.074180Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-10-13T22:18:24.727",
  "references": [
    {
      "source": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
      "url": "https://libreswan.org/security/CVE-2026-77206/"
    },
    {
      "source": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
      "url": "https://libreswan.org/security/CVE-2026-77206/CVE-2026-77206.txt"
    }
  ],
  "sourceIdentifier": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ],
      "source": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
      "type": "Secondary"
    }
  ]
}

CVE-2026-77206 (GCVE-0-2026-77206)

Vulnerability from cvelistv5 – Published: 2026-10-13 21:28 – Updated: 2026-10-16 15:31

Title

IKEv2 pre-authentication Null Pointer Dereference in EAP code

Summary

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-16 15:14 UTC

CWE

CWE-476 - Null Pointer Dereference

Assigner

libreswan CNA under the mitre root

CNA scorecard – unranked: 8 records in the last 180 days, 10 needed details

References

2 references

URL	Tags
https://libreswan.org/security/CVE-2026-77206/CVE…	vendor-advisory
https://libreswan.org/security/CVE-2026-77206/	patch

Impacted products

1 product

Vendor	Product	Version
The Libreswan Project	libreswan	Affected: 4.7 , ≤ 5.3.2 (semver) Affected: 5.4 , ≤ 5.4 (semver) Unaffected: 5.3.3 (semver) Unaffected: 5.4.1 (semver)

Credits

Claude (Anthropic) David Korczynski (ADA Logics Ltd)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-77206",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-16T15:14:41.074180Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-16T15:31:54.304Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://github.com/libreswan/libreswan",
          "defaultStatus": "unaffected",
          "packageName": "libreswan",
          "product": "libreswan",
          "repo": "https://github.com/libreswan/libreswan",
          "vendor": "The Libreswan Project",
          "versions": [
            {
              "lessThanOrEqual": "5.3.2",
              "status": "affected",
              "version": "4.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.4",
              "status": "affected",
              "version": "5.4",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.3.3",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.4.1",
              "versionType": "semver"
            }
          ]
        }
      ],
      "configurations": [
        {
          "lang": "en",
          "value": "Any server or client that accepts IKEv2 connections is vulnerable. The bug can be triggered even if EAP is not configured at all."
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "tool",
          "value": "Claude (Anthropic)"
        },
        {
          "lang": "en",
          "type": "reporter",
          "value": "David Korczynski (ADA Logics Ltd)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Libreswan\u0027s IKEv2 state machine has a null pointer dereference bug in the EAP handling code for authentication. As a result of inconsistency within the IKEv2 state machine code, this bug can be triggered by any IKEv2 connection, even if EAP is not configured at all. The error is caused by a fall-through where it incorrectly dereferences ike-\u003esa.st_eap which is NULL. A malicious IKE_AUTH packet can trigger this bug, meaning the peer does not need to be authenticated. The bug results in a crash and restart of the pluto daemon. No remote code execution is possible. Continued exploitation can cause a denial of service."
        }
      ],
      "exploits": [
        {
          "lang": "en",
          "value": "No known exploitation in the wild. Exploitation requires sending a malicious IKE_AUTH packet and does not require peer authentication."
        }
      ],
      "impacts": [
        {
          "descriptions": [
            {
              "lang": "en",
              "value": "Denial of service via null pointer dereference in EAP handling code when processing malicious IKE_AUTH packets"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        },
        {
          "other": {
            "content": {
              "description": "Vendor-assessed severity: Medium. Exploitation does not require authentication, but the daemon automatically restarts after the crash, requiring continued exploitation for sustained denial of service.",
              "value": "MEDIUM"
            },
            "type": "vendorSeverity"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-476",
              "description": "CWE-476: Null Pointer Dereference",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-13T21:28:11.498Z",
        "orgId": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
        "shortName": "libreswan"
      },
      "references": [
        {
          "name": "Libreswan Security Advisory CVE-2026-77206",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://libreswan.org/security/CVE-2026-77206/CVE-2026-77206.txt"
        },
        {
          "name": "Libreswan CVE-2026-77206 Patches",
          "tags": [
            "patch"
          ],
          "url": "https://libreswan.org/security/CVE-2026-77206/"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Upgrade to libreswan 5.3.3 or 5.4.1 or later. Note that EAP was not functional in libreswan 5.3. If you need EAP support, use 5.4.1 or later. Patches are available at https://libreswan.org/security/CVE-2026-77206/"
        }
      ],
      "source": {
        "defects": [
          "CVE-2026-77206"
        ],
        "discovery": "EXTERNAL"
      },
      "taxonomyMappings": [
        {
          "taxonomyName": "ATT\u0026CK",
          "taxonomyRelations": [
            {
              "relationshipName": "maps to",
              "relationshipValue": "Application or System Exploitation (DoS)",
              "taxonomyId": "T1499.004"
            }
          ],
          "taxonomyVersion": "15.1"
        }
      ],
      "timeline": [
        {
          "lang": "en",
          "time": "2026-08-05T00:00:00.000Z",
          "value": "Libreswan was notified of the issue via security@libreswan.org"
        },
        {
          "lang": "en",
          "time": "2026-09-24T00:00:00.000Z",
          "value": "Advanced notice given to supported customers and distributions"
        },
        {
          "lang": "en",
          "time": "2026-10-05T00:00:00.000Z",
          "value": "Public announcement and release of libreswan 5.3.3 and 5.4.1"
        }
      ],
      "title": "IKEv2 pre-authentication Null Pointer Dereference in EAP code",
      "workarounds": [
        {
          "lang": "en",
          "value": "Apply the available patch or upgrade to a supported version. No configuration-based workaround is available."
        }
      ],
      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
    "assignerShortName": "libreswan",
    "cveId": "CVE-2026-77206",
    "datePublished": "2026-10-13T21:28:11.498Z",
    "dateReserved": "2026-08-20T18:13:09.377Z",
    "dateUpdated": "2026-10-16T15:31:54.304Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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