{
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        "url": "https://www.first.org/tlp/"
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    "lang": "en",
    "notes": [
      {
        "category": "legal_disclaimer",
        "text": "This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Cloud Linux Inc. and provide a link to the original.",
        "title": "Terms of Use"
      }
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          "date": "2026-03-27T09:16:00Z",
          "number": "1",
          "summary": "Initial version"
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          "date": "2026-04-30T17:31:37Z",
          "number": "2",
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      "status": "final",
      "version": "2"
    },
    "title": "Security update on CVE-2026-27856"
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  "vulnerabilities": [
    {
      "cve": "CVE-2026-27856",
      "cwe": {
        "id": "CWE-287",
        "name": "Improper Authentication"
      },
      "notes": [
        {
          "category": "description",
          "text": "Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attack. An attacker can use this to determine the configured credentials. Figuring out the credential will lead into full access to the affected component. Limit access to the doveadm http service port, install fixed version. No publicly available exploits are known.",
          "title": "Vulnerability description"
        },
        {
          "category": "general",
          "text": "The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.",
          "title": "CVSS score applicability"
        }
      ],
      "product_status": {
        "known_affected": [
          "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.i686",
          "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.tuxcare.els1.i686",
          "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.tuxcare.els1.x86_64",
          "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.tuxcare.els2.i686",
          "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.tuxcare.els2.x86_64",
          "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.x86_64"
        ]
      },
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        {
          "category": "self",
          "summary": "Canonical URL",
          "url": "https://cve.tuxcare.com/els/cve/CVE-2026-27856"
        },
        {
          "category": "external",
          "summary": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json",
          "url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json"
        }
      ],
      "release_date": "2026-03-27T09:16:00Z",
      "remediations": [
        {
          "category": "no_fix_planned",
          "details": "This flaw is only exposed if the optional doveadm HTTP listener is explicitly enabled and reachable; in Dovecot’s default configuration that listener is not active, so no network‑accessible attack surface exists unless it has been deliberately configured. Even when reachable, exploitation relies on a high‑complexity timing‑oracle to recover credentials via many precisely timed requests across network jitter, which makes real‑world success unlikely. With no known public exploits and exposure avoidable by restricting access to the doveadm HTTP port, this can be safely deprioritized.",
          "product_ids": [
            "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.i686",
            "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.tuxcare.els1.i686",
            "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.tuxcare.els1.x86_64",
            "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.tuxcare.els2.i686",
            "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.tuxcare.els2.x86_64",
            "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.x86_64"
          ]
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.9,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          },
          "products": [
            "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.i686",
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            "CentOS-8.4:dovecot-devel-1:2.3.8-9.el8.x86_64"
          ]
        }
      ],
      "threats": [
        {
          "category": "impact",
          "details": "Moderate"
        }
      ]
    }
  ]
}