Incorrect Authorization in hMailServer
Summary
| CVE | CVE-2026-114473 |
|---|---|
| State | PUBLISHED |
| Assigner | GitLab |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-10-21 16:17:34 UTC |
| Updated | 2026-10-21 16:17:34 UTC |
| Description | Incorrect authorization in the Sender Rewriting Scheme (SRS) of Progressive Robot hMailServer 6.2.1 through 6.3.6 allows a remote attacker to relay mail through the server to outside addresses. With SRS enabled, the server rewrites the envelope sender of mail it forwards to a signed SRS address at the forwarding domain, and passes a bounce to that address back to the original sender; but it took every message to a valid SRS address, whatever its sender, as delivery to a local recipient, so the relay rules and the SMTP authentication they require were not applied, and the message was delivered to the outside address the SRS address encodes. Anyone holding a valid SRS address of the server, such as the recipient of a forwarded message, could have the server relay mail to the address it encodes for 21 days, and an account holder whose account forwards to an outside mailbox could obtain one for any address. SRS is off by default. |
Risk And Classification
Primary CVSS: v3.1 5 MEDIUM from [email protected]
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N
Problem Types: CWE-863 | CWE-863 CWE-863: Incorrect Authorization
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 5 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N |
| 3.1 | CNA | CVSS | 5 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Progressive Robot Ltd | HMailServer | affected 6.2.1 6.3.6 semver | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| gitlab.com/hmailserver/hmailserver/-/releases/v6.3.7 | [email protected] | gitlab.com | |
| gitlab.com/hmailserver/hmailserver/-/work_items/94 | [email protected] | gitlab.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Upstream hMailServer, whose public pull request 649 fixed the same flaw in its own SRS code; found and fixed in this fork by the hMailServer project's triage of it (Progressive Robot Ltd) (en)
Additional Advisory Data
Solutions
CNA: Upgrade to hMailServer 6.3.7, which takes only a bounce (a null reverse-path) to an SRS address as local delivery and holds any other message to it to the relay rules: where they refuse it, the transaction is refused at DATA or BDAT, and a recipient named after such an address in the same transaction is answered 452 4.5.3. Until then, turn SRS off (SRSEnabled=0, the default).