{"api_version":"1","generated_at":"2026-10-08T14:53:12+00:00","cve":"CVE-2026-107581","urls":{"html":"https://cve.report/CVE-2026-107581","api":"https://cve.report/api/cve/CVE-2026-107581.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-107581","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-107581"},"summary":{"title":"Inefficient Algorithmic Complexity in hMailServer","description":"Progressive Robot hMailServer 6.0.0 through 6.3.5 processes several IMAP commands from a signed-in account in time quadratic in the command's length or in the number of elements it names, and can be made to hold memory out of proportion to a command. The FETCH data-item parser normalised a BODY[] section with a case-insensitive string replacement that copied the whole item per occurrence and split the item list by repeatedly copying the remainder of the command; the server's case-insensitive search compared a needle afresh at every position, so a long SEARCH TEXT key over a message cost the product of the two lengths; SEARCH message sets and the saved-result marker ($), SORT criteria, HEADER.FIELDS name lists and UID ranges were each read once per message rather than once per command; and a FETCH naming a message's sections very many times read and held every section in memory before sending any. An IMAP command may continue past one line through non-synchronizing literals, so one command can reach about eleven megabytes. The IMAP worker threads are a small pool shared with SMTP and POP3, so a signed-in user sending such commands can make the IMAP, SMTP and POP3 services stop responding (CWE-407) and can consume excessive memory (CWE-400).","state":"PUBLISHED","assigner":"GitLab","published_at":"2026-10-08 12:17:16","updated_at":"2026-10-08 12:17:16"},"problem_types":["CWE-407","CWE-407 CWE-407: Inefficient Algorithmic Complexity"],"metrics":[{"version":"3.1","source":"cve@gitlab.com","type":"Secondary","score":"6.5","severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":6.5,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"CVSS","score":"6.5","severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","data":{"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"}}],"references":[{"url":"https://gitlab.com/hmailserver/hmailserver/-/work_items/68","name":"https://gitlab.com/hmailserver/hmailserver/-/work_items/68","refsource":"cve@gitlab.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6","name":"https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6","refsource":"cve@gitlab.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-107581","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-107581","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Progressive Robot Ltd","product":"hMailServer","version":"affected 6.0.0 6.3.6 semver","platforms":[]}],"timeline":[],"solutions":[{"source":"CNA","title":"","value":"Upgrade to hMailServer 6.3.6, which parses the FETCH command and runs the server's case-insensitive string operations in a single pass, reads each SEARCH and UID set and HEADER.FIELDS list once per command, substitutes the saved-result marker once, and refuses a FETCH whose sections add up to many times the message before sending any. 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The FETCH data-item parser normalised a BODY[] section with a case-insensitive string replacement that copied the whole item per occurrence and split the item list by repeatedly copying the remainder of the command; the server's case-insensitive search compared a needle afresh at every position, so a long SEARCH TEXT key over a message cost the product of the two lengths; SEARCH message sets and the saved-result marker ($), SORT criteria, HEADER.FIELDS name lists and UID ranges were each read once per message rather than once per command; and a FETCH naming a message's sections very many times read and held every section in memory before sending any. An IMAP command may continue past one line through non-synchronizing literals, so one command can reach about eleven megabytes. The IMAP worker threads are a small pool shared with SMTP and POP3, so a signed-in user sending such commands can make the IMAP, SMTP and POP3 services stop responding (CWE-407) and can consume excessive memory (CWE-400)."}],"metrics":[{"cvssV3_1":{"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"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-407","description":"CWE-407: Inefficient Algorithmic Complexity","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-10-08T11:47:16.084Z","orgId":"ceab7361-8a18-47b1-92ba-4d7d25f6715a","shortName":"GitLab"},"references":[{"url":"https://gitlab.com/hmailserver/hmailserver/-/work_items/68"},{"url":"https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6"}],"solutions":[{"lang":"en","value":"Upgrade to hMailServer 6.3.6, which parses the FETCH command and runs the server's case-insensitive string operations in a single pass, reads each SEARCH and UID set and HEADER.FIELDS list once per command, substitutes the saved-result marker once, and refuses a FETCH whose sections add up to many times the message before sending any. There is no configuration workaround; the commands require only a signed-in account. Restricting IMAP access to trusted accounts and networks reduces who can send them."}],"title":"Inefficient Algorithmic Complexity in hMailServer"}},"cveMetadata":{"assignerOrgId":"ceab7361-8a18-47b1-92ba-4d7d25f6715a","assignerShortName":"GitLab","cveId":"CVE-2026-107581","datePublished":"2026-10-08T11:47:16.084Z","dateReserved":"2026-10-08T10:52:10.640Z","dateUpdated":"2026-10-08T11:47:16.084Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-08 12:17:16","lastModifiedDate":"2026-10-08 12:17:16","problem_types":["CWE-407","CWE-407 CWE-407: Inefficient Algorithmic Complexity"],"metrics":{"cvssMetricV31":[{"source":"cve@gitlab.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":6.5,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":2.8,"impactScore":3.6}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"107581","Ordinal":"1","Title":"Inefficient Algorithmic Complexity in hMailServer","CVE":"CVE-2026-107581","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"107581","Ordinal":"1","NoteData":"Progressive Robot hMailServer 6.0.0 through 6.3.5 processes several IMAP commands from a signed-in account in time quadratic in the command's length or in the number of elements it names, and can be made to hold memory out of proportion to a command. The FETCH data-item parser normalised a BODY[] section with a case-insensitive string replacement that copied the whole item per occurrence and split the item list by repeatedly copying the remainder of the command; the server's case-insensitive search compared a needle afresh at every position, so a long SEARCH TEXT key over a message cost the product of the two lengths; SEARCH message sets and the saved-result marker ($), SORT criteria, HEADER.FIELDS name lists and UID ranges were each read once per message rather than once per command; and a FETCH naming a message's sections very many times read and held every section in memory before sending any. An IMAP command may continue past one line through non-synchronizing literals, so one command can reach about eleven megabytes. The IMAP worker threads are a small pool shared with SMTP and POP3, so a signed-in user sending such commands can make the IMAP, SMTP and POP3 services stop responding (CWE-407) and can consume excessive memory (CWE-400).","Type":"Description","Title":"Inefficient Algorithmic Complexity in hMailServer"}]}}}