{"id":"CVE-2026-107574","title":"Inefficient algorithmic complexity in the JSON reader of Progressive Robot hMailServer allows a remote unauthenticated attacker to make the mail services unavailable","summary":"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…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-407"],"vendor":"Progressive Robot Ltd","product":"hMailServer","affected":["hMailServer >= 6.2.28 < 6.3.6"],"published":"2026-10-08","updated":"2026-10-08","sourceUpdated":"2026-10-08T21:02:43.860","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-107574","references":[{"url":"https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6","label":"cve@gitlab.com"},{"url":"https://gitlab.com/hmailserver/hmailserver/-/work_items/76","label":"cve@gitlab.com"}],"tags":["nvd","cve.org"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-08T14:15:32.913666Z"},"ingestedAt":"2026-10-08T12:39:48.754Z","slug":"CVE-2026-107574","body":"## Overview\n\nInefficient 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}