Uncontrolled Session Eviction in Progressive Robot hMailServer
CVE-2026-107586

4.3MEDIUM

Key Information:

Vendor

Progressive Robot Ltd

Status
Hmailserver
Vendor
CVE Published:
8 October 2026

What is CVE-2026-107586?

An issue in Progressive Robot hMailServer's browser session table within the REST API allows remote authenticated users to disrupt other users' sessions. When the session table reaches its capacity, it indiscriminately evicts the least recently used session, regardless of ownership. This design flaw permits users to over-sign into their accounts, leading to the potential to terminate idle sessions of other users, including webmail and administrative accounts. This vulnerability poses a significant risk to user privacy and operational continuity.

Affected Version(s)

hMailServer 6.2.28 < 6.3.6

References

https://gitlab.com/hmailserver/hmailserver/-/work_items/62
https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6

CVSS V3.1

Score:
4.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Found in the hMailServer project's own security review (Progressive Robot Ltd)
.