CVE-2026-107584
Not Failing Securely ('Failing Open') in hMailServer
02 Description
Not Failing Securely ('Failing Open') in hMailServer
03 Exploitation and scoring
- Exploitation
- Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
- SSVC decision
- ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
- AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
- Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.
- EPSS probability
- 0.15% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 3.7% of scored records. A rank, not a probability.
- NVD base score
- 7.4 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- NVD analysis status
- Deferred. NVD last modified this record on 2026-10-08.
- Red Hat severity
- No Red Hat rating. Red Hat rates the CVEs that affect its products.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2026-10-08 11:49Z21 DAYS AGO
- Last updated
- 2026-10-08 17:34Z20 DAYS AGO
- Reserved
- 2026-10-08
- Assigning CNA
- GitLab
- Record state
- PUBLISHED
- Severity
- High (CVSS 7.4)
- CNA CVSS vector
- CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- Weaknesses
- CWE-636Not Failing Securely ('Failing Open')Class
- Data version
- 5.2
- Document digest
- 2552b05317f42b860130cb91ee90634e9dacec8141ce392d7a72fa3b61c24688
05 Affected products
06 References
07 Remediation
Upgrade to hMailServer 6.3.6, which treats an incomplete, unsigned or unproven DNSSEC answer for a TLSA or MX lookup under a signed zone as indeterminate, does not use a mail exchanger whose lookup was indeterminate, defers the delivery when none is left, delivers only to mail exchangers named by a DNSSEC-validated MX record set, and (for a host whose DNS servers are IPv6 only) asks those IPv6 servers. Until then, for each recipient domain whose mail must be protected, an SMTP route that names its mail exchangers with the connection security 'STARTTLS (required)', with remote certificate verification on (VerifyRemoteSslCertificate=1), prevents delivery in cleartext or to another host for that domain; and the server's DNS resolver should be one reached over a trusted path, such as a validating resolver on the same host.