FKIE_CVE-2026-40203

Vulnerability from fkie_nvd - Published: 2026-08-28 12:16 - Updated: 2026-09-03 18:13
Severity
3.7 (Low) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Summary
When IMAP compression is enabled, the same compression state is reused across responses in a session, so response sizes depend on both attacker-supplied mail and other mail in the same mailbox. An attacker that can send mail to a user and can also observe the sizes of that user's IMAP traffic can confirm whether the body of a small message matches a guessed text. Recovery of arbitrary unknown content was not demonstrated, but the attack can disclose whether a secret-like message body matches a candidate. Disable IMAP compression. Update to non-vulnerable version. No publicly available exploits are known.
References
security@open-xchange.comhttps://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0003.json
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "modules": [
            "core"
          ],
          "product": "OX Dovecot Pro",
          "vendor": "Open-Xchange GmbH",
          "versions": [
            {
              "lessThan": "2.3.22.2",
              "status": "affected",
              "version": "2.3.0",
              "versionType": "semver"
            },
            {
              "lessThan": "3.0.7",
              "status": "affected",
              "version": "3.0.0",
              "versionType": "semver"
            },
            {
              "lessThan": "3.1.6",
              "status": "affected",
              "version": "3.1.0",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "modules": [
            "core"
          ],
          "product": "OX Dovecot CE",
          "vendor": "Open-Xchange GmbH",
          "versions": [
            {
              "lessThan": "2.4.5",
              "status": "affected",
              "version": "2.3.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "security@open-xchange.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "When IMAP compression is enabled, the same compression state is reused across responses in a session, so response sizes depend on both attacker-supplied mail and other mail in the same mailbox. An attacker that can send mail to a user and can also observe the sizes of that user\u0027s IMAP traffic can confirm whether the body of a small message matches a guessed text. Recovery of arbitrary unknown content was not demonstrated, but the attack can disclose whether a secret-like message body matches a candidate. Disable IMAP compression. Update to non-vulnerable version. No publicly available exploits are known."
    }
  ],
  "id": "CVE-2026-40203",
  "lastModified": "2026-09-03T18:13:44.643",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 3.7,
          "baseSeverity": "LOW",
          "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:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 1.4,
        "source": "security@open-xchange.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-40203",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-28T14:56:57.150012Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-28T12:16:28.897",
  "references": [
    {
      "source": "security@open-xchange.com",
      "url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0003.json"
    }
  ],
  "sourceIdentifier": "security@open-xchange.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-200"
        }
      ],
      "source": "security@open-xchange.com",
      "type": "Secondary"
    }
  ]
}



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