CVE-2026-107569
- Source
- https://cve.org/CVERecord?id=CVE-2026-107569
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-107569.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2026-107569
- Published
- 2026-10-19T15:34:37Z
- Modified
- 2026-10-20T02:46:34Z
- Severity
-
- 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
- Summary
- Unchecked Input for Loop Condition in hMailServer
- Details
-
Unchecked input for a loop condition in Progressive Robot hMailServer 6.0.0 through 6.3.6 allows a remote unauthenticated attacker to stop the server carrying mail. The server bounds the mail it generates in response to a message - a rule forward, reply or copy, an account forward, a Sieve redirect, vacation or notify, a bounce, an out-of-office reply - by a counter it carries in the message's X-hMailServer-LoopCount header, and makes no more once the counter reaches the configured rule loop limit (5 by default); that is what ends a forwarding or auto-reply cycle in a bounded number of hops. X-hMailServer-LoopCount is an ordinary header that is not stripped from mail arriving from outside, and the server read it with a signed conversion and no validation, so a count below zero passed every test against the limit: a sender who sets X-hMailServer-LoopCount to a negative value, or on the Linux builds to a value above the 32-bit signed range that the conversion wraps to a negative one, lifts the bound, and a message that enters a generated-mail cycle then loops up to about two thousand million times, each hop a queued message and a delivery, filling the queue and disk and stopping mail service. The Sieve notify action (from 6.2.22) consulted no limit at all, and its increment of the count could overflow a signed integer; and an account could reset the counter on its own mail through a Sieve editheader of the header (from 6.2.22) or a rule Set header value action (all versions) ahead of a forward or redirect.
- Database specific
{ "cna_assigner": "GitLab", "cwe_ids": [ "CWE-606" ], "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107569.json" }- References