FKIE_CVE-2026-107572

Vulnerability from fkie_nvd - Published: 2026-10-08 12:17 - Updated: 2026-10-08 21:02
Severity
6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
Inefficient complexity in the Sieve filter evaluation of Progressive Robot hMailServer 6.2.24 through 6.3.5 allows an authenticated account holder to make the mail services unavailable with their own filter. A ':matches' pattern was matched by a backtracking descent whose time grew with the matched value's length raised to the number of wildcards, so a pattern such as '*a*a*a*b' over 800 characters took 44 seconds; and 'deleteheader' erased the fields it removed one at a time, so removing many fields of one name over a message's header cost O(N^2) (80,000 fields took 18.8 seconds). Sieve filters run on the small, shared delivery thread pool, so an account holder whose active script does this, fed a few messages they can send themselves, empties the pool and stops delivery for the whole server. The script is the account holder's own and cannot be set for another user.
References
cve@gitlab.comhttps://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6
cve@gitlab.comhttps://gitlab.com/hmailserver/hmailserver/-/work_items/75
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "hMailServer",
          "repo": "https://gitlab.com/hmailserver/hmailserver",
          "vendor": "Progressive Robot Ltd",
          "versions": [
            {
              "lessThan": "6.3.6",
              "status": "affected",
              "version": "6.2.24",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "cve@gitlab.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Inefficient complexity in the Sieve filter evaluation of Progressive Robot hMailServer 6.2.24 through 6.3.5 allows an authenticated account holder to make the mail services unavailable with their own filter. A \u0027:matches\u0027 pattern was matched by a backtracking descent whose time grew with the matched value\u0027s length raised to the number of wildcards, so a pattern such as \u0027*a*a*a*b\u0027 over 800 characters took 44 seconds; and \u0027deleteheader\u0027 erased the fields it removed one at a time, so removing many fields of one name over a message\u0027s header cost O(N^2) (80,000 fields took 18.8 seconds). Sieve filters run on the small, shared delivery thread pool, so an account holder whose active script does this, fed a few messages they can send themselves, empties the pool and stops delivery for the whole server. The script is the account holder\u0027s own and cannot be set for another user."
    }
  ],
  "id": "CVE-2026-107572",
  "lastModified": "2026-10-08T21:02:43.860",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 3.6,
        "source": "cve@gitlab.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-107572",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-08T17:35:04.470485Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-10-08T12:17:14.870",
  "references": [
    {
      "source": "cve@gitlab.com",
      "url": "https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6"
    },
    {
      "source": "cve@gitlab.com",
      "url": "https://gitlab.com/hmailserver/hmailserver/-/work_items/75"
    }
  ],
  "sourceIdentifier": "cve@gitlab.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-1333"
        }
      ],
      "source": "cve@gitlab.com",
      "type": "Secondary"
    }
  ]
}



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