CVE-2026-107586

Status: DeferredMedium (4.3)—

Uncontrolled eviction in the browser session table of the REST API in Progressive Robot hMailServer 6.2.28 through 6.3.5 allows a remote authenticated user to end other users' sessions. The table of browser sessions, shared by every account, the server administrator and support sessions, dropped its least recently used session whenever it was full, whoever it belonged to, and placed no limit on how many sessions one account could hold. A user who repeatedly signs in with their own mailbox password can therefore keep the table full and sign out every webmail and administration session that is idle for more than a short time, for as long as they continue.

CVSS

Version: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Base score: 4.3

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.34%
Percentile among all scored CVEs: 25
Score date: 10/13/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

ExploitationT1210 Exploitation of Remote Serviceslateral movement85 %
Primary impactT1531 Account Access Removalimpact80 %
Secondary impactT1499.004 Application or System Exploitationimpact75 %

Vulnerabilidad en servicio remoto (REST API) que requiere autenticación previa (PR:L). Impacto: cierre forzado de sesiones de otros usuarios (T1531) y negación de servicio de disponibilidad de sesiones (T1499.004). CWE-770 (desalojo incontrolado).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Vulnerability Scanning Threat Intelligence Program Privileged Account Management Network Segmentation Filter Network Traffic Disable or Remove Feature or Program

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Hmailserver — Hmailserver^AI

CWEs

CWE-770

References

Raw JSON (NVD)

Show

{
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        "ssvcData": {
          "id": "CVE-2026-107586",
          "role": "CISA Coordinator",
          "options": [
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              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
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              "technicalImpact": "partial"
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          "version": "2.0.3",
          "timestamp": "2026-10-08T19:12:40.221197Z"
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          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "LOW",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
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      "affectedData": [
        {
          "repo": "https://gitlab.com/hmailserver/hmailserver",
          "vendor": "Progressive Robot Ltd",
          "product": "hMailServer",
          "versions": [
            {
              "status": "affected",
              "version": "6.2.28",
              "lessThan": "6.3.6",
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  "published": "2026-10-08T15:17:44.897",
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      "url": "https://gitlab.com/hmailserver/hmailserver/-/work_items/62",
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      "value": "Uncontrolled eviction in the browser session table of the REST API in Progressive Robot hMailServer 6.2.28 through 6.3.5 allows a remote authenticated user to end other users' sessions. The table of browser sessions, shared by every account, the server administrator and support sessions, dropped its least recently used session whenever it was full, whoever it belonged to, and placed no limit on how many sessions one account could hold. A user who repeatedly signs in with their own mailbox password can therefore keep the table full and sign out every webmail and administration session that is idle for more than a short time, for as long as they continue."
    }
  ],
  "lastModified": "2026-10-08T21:02:43.860",
  "sourceIdentifier": "cve@gitlab.com"
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