{"id":"CVE-2026-107574","summary":"Inefficient Algorithmic Complexity in hMailServer","details":"Inefficient algorithmic complexity in the JSON reader of Progressive Robot hMailServer allows a remote unauthenticated attacker to make the mail services unavailable. Reading a JSON object kept the first of each duplicated member name by searching the members already read, so an object of N distinct member names cost O(N^2): 1 MB took 8.9 seconds and 4 MB took 300 seconds against the affected code. A remote attacker reaches the reader without an account by mailing a crafted TLS-RPT report (up to 16 MB after decompression) to a hosted domain's published report mailbox, which is read on a delivery thread; a few such reports hold every delivery thread (ten by default), so the server delivers no mail, local or outbound, for over an hour per report. A signed-in account reaches the same 16 MB body through the webmail's own REST routes, holding the REST API's own worker threads. Where no report mailbox is configured, the unauthenticated REST sign-in routes that read a JSON body are capped at 64 KB and are not affected.","modified":"2026-10-10T02:47:27.658778061Z","published":"2026-10-08T11:46:26.206Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107574.json","cna_assigner":"GitLab","cwe_ids":["CWE-407"]},"references":[{"type":"WEB","url":"https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6"},{"type":"WEB","url":"https://gitlab.com/hmailserver/hmailserver/-/work_items/76"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107574.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-107574"},{"type":"PACKAGE","url":"https://gitlab.com/hmailserver/hmailserver"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://gitlab.com/hmailserver/hmailserver","events":[{"introduced":"f088336c208817816c87c88c0ede7bb079c2a6ab"},{"fixed":"e3c448aa66fc310b74d076884d54fae951296915"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"6.2.28"},{"fixed":"6.3.6"}]}}],"versions":["v6.3.5","v6.3.4","v6.3.3","v6.3.2","build-inputs-1","v6.3.1","v6.3.0","v6.2.28"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-107574.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}