CVE-2026-107585
Allocation of Resources Without Limits or Throttling in hMailServer
No known exploitation. EPSS puts it in the 37th percentile. Fixed in 6.3.6.
What to do
Find your product and version, then upgrade to the build on the right.
- Progressive Robot Ltd hMailServerAffected: ≥ 6.3.4, < 6.3.6Upgrade to: 6.3.6Stated by: CVE record
Versions as the sources state them. Full version matrix after sign-in
What it is
From the CVE record
Uncontrolled eviction in the pending sign-in tables of the REST API in Progressive Robot hMailServer 6.3.4 and 6.3.5 allows a remote unauthenticated attacker to make other users' OpenID Connect, SAML and passkey sign-ins fail. The routes that start a single sign-on and hand out a passkey sign-in challenge are reached without authentication and stored pending state in bounded tables that dropped their oldest entry when full, whoever had started it. An attacker who starts sign-ins a few times a second (about a hundred a second for passkeys) pushes every other user's pending sign-in out of the table before that user's browser returns, denying single sign-on and passkey sign-in for as long as the requests continue.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.4% chance of exploitation activity in the next 30 days, which ranks it in the 37th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
7 events over 0 days, from the signal feeds we watch.
- Patch availablepatch available, published, weakness classified, att&ck mapped, record updated, record updated
Affected products
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Scored 5.3 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity LowNo special conditions — the attack can be reliably reproduced
- Privileges Required NoneNo authentication required — anyone can exploit this
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality NoneNo confidentiality impact
- Integrity NoneNo integrity impact
- Availability LowReduced performance or intermittent disruption of service
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
Sources
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