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

Vulnerability from cvelistv5 – Published: 2026-10-13 21:28 – Updated: 2026-10-13 21:28
VLAI
Title
IKEv2 pre-authentication Null Pointer Dereference in EAP code
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.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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
Impacted products
Vendor Product Version CPE status
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)
guessed Create a notification for this product.
Credits
Claude (Anthropic) David Korczynski (ADA Logics Ltd)
Show details on NVD website
To clipboard 

{
  "containers": {
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        {
          "collectionURL": "https://github.com/libreswan/libreswan",
          "defaultStatus": "unaffected",
          "packageName": "libreswan",
          "product": "libreswan",
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          "versions": [
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              "status": "affected",
              "version": "4.7",
              "versionType": "semver"
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          "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": [
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          "type": "tool",
          "value": "Claude (Anthropic)"
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          "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": [
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          "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": [
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              "lang": "en",
              "value": "Denial of service via null pointer dereference in EAP handling code when processing malicious IKE_AUTH packets"
            }
          ]
        }
      ],
      "metrics": [
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            "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"
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              "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"
          }
        }
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          "descriptions": [
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      "providerMetadata": {
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        "orgId": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
        "shortName": "libreswan"
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      "references": [
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          "name": "Libreswan Security Advisory CVE-2026-77206",
          "tags": [
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          "url": "https://libreswan.org/security/CVE-2026-77206/CVE-2026-77206.txt"
        },
        {
          "name": "Libreswan CVE-2026-77206 Patches",
          "tags": [
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          ],
          "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": {
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        "discovery": "EXTERNAL"
      },
      "taxonomyMappings": [
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          "taxonomyRelations": [
            {
              "relationshipName": "maps to",
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      "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."
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      "x_generator": {
        "engine": "cvelib 1.8.0"
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  },
  "cveMetadata": {
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    "assignerShortName": "libreswan",
    "cveId": "CVE-2026-77206",
    "datePublished": "2026-10-13T21:28:11.498Z",
    "dateReserved": "2026-08-20T18:13:09.377Z",
    "dateUpdated": "2026-10-13T21:28:11.498Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
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        "cveTags": [],
        "descriptions": [
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            "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": "2026-10-13T22:18:24.727",
        "metrics": {
          "cvssMetricV31": [
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              "source": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
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        "references": [
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            "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"
          }
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        "sourceIdentifier": "d42dc95b-23f1-4e06-9076-20753a0fb0df",
        "vulnStatus": "Received",
        "weaknesses": [
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                "lang": "en",
                "value": "CWE-476"
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            "type": "Secondary"
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      "cve": "CVE-2026-77206",
      "id": "CVE-2026-77206",
      "initial_release_date": "2026-10-05T00:00:00+00:00",
      "product_status:known_affected": "12",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "libreswan: IKEv2 pre-authentication Null Pointer deref in EAP code",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-77206.json",
      "version": "3"
    }
  }
}



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