CVE-2026-107567
Use of Less Trusted Source in hMailServer
02 Description
Use of Less Trusted Source 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.
- AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
- Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
- EPSS probability
- 0.16% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 5.4% of scored records. A rank, not a probability.
- NVD base score
- 7.5 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- NVD analysis status
- Deferred. NVD last modified this record on 2026-10-20.
- 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
- 2026-10-19 15:34Z9 DAYS AGO
- Last updated
- 2026-10-20 19:26Z8 DAYS AGO
- Reserved
- 2026-10-08
- Assigning CNA
- GitLab
- Record state
- PUBLISHED
- Severity
- High (CVSS 7.5)
- CNA CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- Weaknesses
- CWE-348Use of Less Trusted SourceBase
- Data version
- 5.2
- Document digest
- 4779cb8f01212584b3c6777cd2f28094a096b5bc70bacecce88d05714ca3e85f
05 Affected products
06 References
07 Remediation
Upgrade to hMailServer 6.3.7. It records on each message, and on every copy of it, whether the message came from outside: an SMTP session that did not authenticate and was not a submission the server's IP ranges allow without authentication, a download from an external account, or an imported file. It signs a message as its From domain only when an authenticated user submitted it (as another domain the server hosts only when the account may send as the address its From names), the server made it, or an IP range let it in as one of the server's own domains, so mail from outside and its forwards keep only the signatures they arrived with, and a signed-in account's message from an address at another hosted domain that the account may not send as is sent unsigned as that domain. Until then, do one of the following: publish a DMARC policy of quarantine or reject for each hosted domain the server signs for and set the server's DMARC failure score (DMARCFailureScore) at or above the spam delete threshold (SpamDeleteThreshold), so that such a message is refused on arrival; refuse it in an OnAcceptMessage event script when the client has not authenticated and the From header names a domain the server signs for; remove the forwards, rule forwards, Sieve redirects, alias and list members and mirror addresses that carry mail to outside addresses; or disable DKIM signing for the hosted domains, which alone of these also covers a signed-in account's submission. Rotate the DKIM key of any