{"id":"CVE-2026-103010","state":"PUBLISHED","title":"Heap-based Buffer Overflow in hMailServer","description":"Heap-based buffer overflow in the legacy Blowfish decryption routine (BlowFishEncryptor::DecryptFromString) in Progressive Robot hMailServer 6.0.0 through 6.3.3 on Windows allows a local interactive user with no hMailServer credentials to write bytes of their choosing past the end of a 255-byte heap buffer in the hMailServer service process, which runs as LocalSystem by default. The user does this by passing a long hexadecimal string to the COM method Utilities.BlowfishDecrypt, which checked no authentication. The routine converted hexadecimal input of any length into a fixed 255-byte buffer before decrypting it in place. The result is a denial of service (service crash), and possibly code execution with the privileges of the service account.","publishedAt":"2026-10-08T10:53:10.627Z","updatedAt":"2026-10-08T14:22:28.966Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"GitLab"},"assigner":"GitLab","products":["Progressive Robot Ltd hMailServer"],"affected":[{"vendor":"Progressive Robot Ltd","product":"hMailServer","defaultStatus":"unaffected","versions":[{"version":"6.0.0","status":"affected","lessThan":"6.3.4","versionType":"semver"}],"repo":"https://gitlab.com/hmailserver/hmailserver"}],"references":["https://gitlab.com/hmailserver/hmailserver/-/commit/135a1908ff820ed587d5f180f98c53bd010d8931","https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.4","https://gitlab.com/hmailserver/hmailserver/-/work_items/49"],"weaknesses":["CWE-122"],"ingestedAt":"2026-10-29T20:10:23.711Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/103xxx/CVE-2026-103010.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-103010","state":"PUBLISHED","datePublished":"2026-10-08T10:53:10.627Z","dateUpdated":"2026-10-08T14:22:28.966Z","assignerShortName":"GitLab","assignerOrgId":"ceab7361-8a18-47b1-92ba-4d7d25f6715a","dateReserved":"2026-09-29T21:04:45.349Z"},"containers":{"cna":{"title":"Heap-based Buffer Overflow in hMailServer","descriptions":[{"lang":"en","value":"Heap-based buffer overflow in the legacy Blowfish decryption routine (BlowFishEncryptor::DecryptFromString) in Progressive Robot hMailServer 6.0.0 through 6.3.3 on Windows allows a local interactive user with no hMailServer credentials to write bytes of their choosing past the end of a 255-byte heap buffer in the hMailServer service process, which runs as LocalSystem by default. The user does this by passing a long hexadecimal string to the COM method Utilities.BlowfishDecrypt, which checked no authentication. The routine converted hexadecimal input of any length into a fixed 255-byte buffer before decrypting it in place. The result is a denial of service (service crash), and possibly code execution with the privileges of the service account."}],"affected":[{"vendor":"Progressive Robot Ltd","product":"hMailServer","defaultStatus":"unaffected","versions":[{"version":"6.0.0","status":"affected","lessThan":"6.3.4","versionType":"semver"}],"repo":"https://gitlab.com/hmailserver/hmailserver"}],"references":[{"url":"https://gitlab.com/hmailserver/hmailserver/-/commit/135a1908ff820ed587d5f180f98c53bd010d8931"},{"url":"https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.4"},{"url":"https://gitlab.com/hmailserver/hmailserver/-/work_items/49"}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH","baseScore":7.8,"baseSeverity":"HIGH"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-122","lang":"en","description":"CWE-122: Heap-based Buffer Overflow","type":"CWE"}]}],"providerMetadata":{"shortName":"GitLab","orgId":"ceab7361-8a18-47b1-92ba-4d7d25f6715a","dateUpdated":"2026-10-08T10:53:10.627Z"},"solutions":[{"lang":"en","value":"Upgrade to hMailServer 6.3.6, which also requires authentication for the COM Utilities helpers (6.3.4 is the first release with this routine fixed)."}],"credits":[{"lang":"en","value":"Found in the hMailServer project's own code review (Progressive Robot Ltd)","type":"finder"}]},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-08T14:22:18.436893Z","id":"CVE-2026-103010","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-08T14:22:28.966Z"}}]}}}