FKIE_CVE-2026-40687

Vulnerability from fkie_nvd - Published: 2026-04-30 22:16 - Updated: 2026-06-17 10:45
Severity
4.8 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Summary
In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there can be an out-of-bounds write that crashes the connection instance, or erroneous data processing that divulges data from uninitialized heap memory.
References
cve@mitre.orghttps://code.exim.org/exim/exim/commit/68b963b9f75ca27b38e1c0f8c87037990199f505Patch
cve@mitre.orghttps://exim.org/static/doc/security/CVE-2026-40687.txtBroken Link
cve@mitre.orghttps://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40687.assessmentVendor Advisory
cve@mitre.orghttps://www.openwall.com/lists/oss-security/2026/04/30/21Mailing List, Third Party Advisory
Impacted products
Vendor Product Version
exim exim *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Exim",
          "vendor": "Exim",
          "versions": [
            {
              "lessThan": "4.99.2",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "cve@mitre.org"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "E48EAA99-95DA-4695-BBEA-16D09AA0A508",
              "versionEndExcluding": "4.99.2",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there can be an out-of-bounds write that crashes the connection instance, or erroneous data processing that divulges data from uninitialized heap memory."
    }
  ],
  "id": "CVE-2026-40687",
  "lastModified": "2026-06-17T10:45:34.567",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 4.8,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 2.5,
        "source": "cve@mitre.org",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.1,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.2,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-40687",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-05-01T14:25:03.813157Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-04-30T22:16:25.923",
  "references": [
    {
      "source": "cve@mitre.org",
      "tags": [
        "Patch"
      ],
      "url": "https://code.exim.org/exim/exim/commit/68b963b9f75ca27b38e1c0f8c87037990199f505"
    },
    {
      "source": "cve@mitre.org",
      "tags": [
        "Broken Link"
      ],
      "url": "https://exim.org/static/doc/security/CVE-2026-40687.txt"
    },
    {
      "source": "cve@mitre.org",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40687.assessment"
    },
    {
      "source": "cve@mitre.org",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "url": "https://www.openwall.com/lists/oss-security/2026/04/30/21"
    }
  ],
  "sourceIdentifier": "cve@mitre.org",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-909"
        }
      ],
      "source": "cve@mitre.org",
      "type": "Secondary"
    }
  ]
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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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.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.