{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-107585","assignerOrgId":"ceab7361-8a18-47b1-92ba-4d7d25f6715a","state":"PUBLISHED","assignerShortName":"GitLab","dateReserved":"2026-10-08T10:52:30.638Z","datePublished":"2026-10-08T15:11:19.477Z","dateUpdated":"2026-10-08T19:13:35.529Z"},"containers":{"cna":{"title":"Allocation of Resources Without Limits or Throttling in hMailServer","descriptions":[{"lang":"en","value":"Uncontrolled eviction in the pending sign-in tables of the REST API in Progressive Robot hMailServer 6.3.4 and 6.3.5 allows a remote unauthenticated attacker to make other users' OpenID Connect, SAML and passkey sign-ins fail. The routes that start a single sign-on and hand out a passkey sign-in challenge are reached without authentication and stored pending state in bounded tables that dropped their oldest entry when full, whoever had started it. An attacker who starts sign-ins a few times a second (about a hundred a second for passkeys) pushes every other user's pending sign-in out of the table before that user's browser returns, denying single sign-on and passkey sign-in for as long as the requests continue."}],"affected":[{"vendor":"Progressive Robot Ltd","product":"hMailServer","repo":"https://gitlab.com/hmailserver/hmailserver","versions":[{"version":"6.3.4","status":"affected","lessThan":"6.3.6","versionType":"semver"}],"defaultStatus":"unaffected"}],"problemTypes":[{"descriptions":[{"lang":"en","description":"CWE-770: Allocation of Resources Without Limits or Throttling","cweId":"CWE-770","type":"CWE"}]}],"references":[{"url":"https://gitlab.com/hmailserver/hmailserver/-/work_items/63"},{"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:L/PR:N/UI:N/S:U/C:N/I:N/A:L","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"LOW","baseScore":5.3,"baseSeverity":"MEDIUM"}}],"solutions":[{"lang":"en","value":"Upgrade to hMailServer 6.3.6, in which a pending OpenID Connect, SAML or passkey sign-in is no longer held on the server at all but carried by the browser in a cookie sealed with AES-256-GCM under a key held only in memory and good once, so there is no table a flood of unauthenticated starts can fill. Until then: limit the rate of /portal/oidc/start, /portal/saml/start and /api/v1/passkeys/challenge per client at a reverse proxy, and keep password sign-in available for administrators."}],"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":"2026-10-08T15:11:19.477Z"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-08T19:13:25.557624Z","id":"CVE-2026-107585","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-10-08T19:13:35.529Z"}}]}}