{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-103647", "assignerOrgId": "ceab7361-8a18-47b1-92ba-4d7d25f6715a", "state": "PUBLISHED", "assignerShortName": "GitLab", "dateReserved": "2026-10-01T07:04:34.908Z", "datePublished": "2026-10-08T10:53:05.628Z", "dateUpdated": "2026-10-08T14:22:56.590Z"}, "containers": {"cna": {"title": "Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in hMailServer", "descriptions": [{"lang": "en", "value": "Cross-site scripting in the webmail of Progressive Robot hMailServer 6.3.2 through 6.3.5 allows a remote attacker who can send a user an encrypted message to run script in the webmail's origin with that user's session. When the webmail decrypted an S/MIME message (from 6.3.2) or an OpenPGP message (from 6.3.4) in the browser, it offered each decrypted attachment as a blob URL of the media type the message declared for it. A click saved the file, but if the user opened the attachment in a new tab, a part declared as text/html was rendered as a document of the webmail's origin and its script could read the mailbox, send mail and change the account through the REST API. The webmail is served only when the REST API is enabled, which it is not by default."}], "affected": [{"vendor": "Progressive Robot Ltd", "product": "hMailServer", "repo": "https://gitlab.com/hmailserver/hmailserver", "versions": [{"version": "6.3.2", "status": "affected", "lessThan": "6.3.6", "versionType": "semver"}], "defaultStatus": "unaffected"}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')", "cweId": "CWE-79", "type": "CWE"}]}], "references": [{"url": "https://gitlab.com/hmailserver/hmailserver/-/work_items/52"}, {"url": "https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6"}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE", "baseScore": 8, "baseSeverity": "HIGH"}}], "solutions": [{"lang": "en", "value": "Upgrade to hMailServer 6.3.6, which hands every decrypted attachment to the browser as application/octet-stream so that it is only ever saved. Until then: keep the REST API off (RestApiPort 0, the default), or tell webmail users not to open decrypted attachments in a new tab."}], "credits": [{"lang": "en", "value": "Found in the hMailServer project's own security review (Progressive Robot Ltd)", "type": "finder"}], "providerMetadata": {"orgId": "ceab7361-8a18-47b1-92ba-4d7d25f6715a", "shortName": "GitLab", "dateUpdated": "2026-10-08T10:53:05.628Z"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-10-08T14:22:42.954493Z", "id": "CVE-2026-103647", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-08T14:22:56.590Z"}}]}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "hMailServer", "repo": "https://gitlab.com/hmailserver/hmailserver", "vendor": "Progressive Robot Ltd", "versions": [{"lessThan": "6.3.6", "status": "affected", "version": "6.3.2", "versionType": "semver"}]}], "source": "cve@gitlab.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Cross-site scripting in the webmail of Progressive Robot hMailServer 6.3.2 through 6.3.5 allows a remote attacker who can send a user an encrypted message to run script in the webmail's origin with that user's session. When the webmail decrypted an S/MIME message (from 6.3.2) or an OpenPGP message (from 6.3.4) in the browser, it offered each decrypted attachment as a blob URL of the media type the message declared for it. A click saved the file, but if the user opened the attachment in a new tab, a part declared as text/html was rendered as a document of the webmail's origin and its script could read the mailbox, send mail and change the account through the REST API. The webmail is served only when the REST API is enabled, which it is not by default."}], "id": "CVE-2026-103647", "lastModified": "2026-10-08T11:16:42.950", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.0, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 1.6, "impactScore": 5.8, "source": "cve@gitlab.com", "type": "Secondary"}]}, "published": "2026-10-08T11:16:42.950", "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/52"}], "sourceIdentifier": "cve@gitlab.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-79"}], "source": "cve@gitlab.com", "type": "Primary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[6.3.2,6.3.6)"}}], "enrichment": {"confidence": 95.0, "confidence_source": "inferred", "scores": [{"score": 95.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "hMailServer", "source": "cna", "vendor": "Progressive Robot Ltd"}, "product": "hmailserver", "vendor": "progressive_robot"}], "created": "2026-10-08T12:45:17.926121+00:00", "updated": "2026-10-08T13:00:07.553276+00:00", "vendors": ["progressive_robot", "progressive_robot$PRODUCT$hmailserver"]}