Uncontrolled Eviction Vulnerability in Progressive Robot hMailServer
CVE-2026-107585

5.3MEDIUM

Key Information:

Vendor

Progressive Robot Ltd

Status
Hmailserver
Vendor
CVE Published:
8 October 2026

What is CVE-2026-107585?

The uncontrolled eviction vulnerability found in the pending sign-in tables of the REST API in hMailServer versions 6.3.4 and 6.3.5 can be exploited by remote unauthenticated attackers. It allows attackers to interfere with legitimate users' OpenID Connect, SAML, and passkey sign-ins. The flawed implementation allows an attacker to initiate sign-ins rapidly, effectively pushing legitimate users' sign-in requests out of the system's pending tables. This disruption results in users being unable to authenticate for as long as the attack persists, significantly compromising the security and user experience of the service.

Affected Version(s)

hMailServer 6.3.4 < 6.3.6

References

https://gitlab.com/hmailserver/hmailserver/-/work_items/63
https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

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