CVE-2026-56583 Overview
CVE-2026-56583 affects HCL MyCloud with a concurrent login weakness classified under [CWE-613] Insufficient Session Expiration. The application permits the same user account to maintain multiple simultaneous authenticated sessions without enforcing session restrictions. This condition raises the risk of unauthorized access, session hijacking, and account misuse when credentials are shared or stolen. The vulnerability is exploitable over the network but requires low privileges and high attack complexity, limiting practical impact to confidentiality only.
Critical Impact
An attacker with valid or stolen credentials can maintain concurrent sessions alongside the legitimate user, enabling silent unauthorized access and session misuse without triggering logout of the original session.
Affected Products
- HCL MyCloud (specific affected versions are not enumerated in the public advisory)
Discovery Timeline
- 2026-07-21 - CVE-2026-56583 published to the National Vulnerability Database
- 2026-07-22 - Last updated in NVD database
Technical Details for CVE-2026-56583
Vulnerability Analysis
The flaw is a session management weakness in HCL MyCloud. The application does not restrict or invalidate prior authenticated sessions when a user authenticates from a new client. Multiple valid session tokens can therefore exist concurrently for the same identity. This behavior maps to [CWE-613] Insufficient Session Expiration.
The EPSS score is 0.14% with a percentile of 3.814, indicating a low probability of exploitation in the near term. No public proof-of-concept, exploit code, or CISA KEV listing is associated with this CVE at the time of publication. Impact is limited to confidentiality: an attacker cannot modify data or disrupt availability through this weakness alone.
Root Cause
The root cause is the absence of a single-session policy or concurrent-session limit in HCL MyCloud's authentication layer. When a user logs in, existing sessions bound to that account are neither invalidated nor flagged. The application also does not surface active session state to the user, preventing them from detecting parallel logins.
Attack Vector
Exploitation requires network access to the MyCloud login interface and possession of valid credentials, obtained through phishing, credential stuffing, password reuse, or insider access. The attacker authenticates while the legitimate user's session remains active. Both sessions operate independently, giving the attacker persistent access aligned to the victim's entitlements. High attack complexity reflects the prerequisite of already-valid credentials and the absence of privilege escalation from this flaw alone.
No verified exploit code is available. Refer to the HCL Software Knowledge Base Article for vendor guidance.
Detection Methods for CVE-2026-56583
Indicators of Compromise
- Multiple active session identifiers bound to a single user account across differing source IP addresses or user-agent strings.
- Authentication events for the same account originating from geographically distant locations within short time windows.
- Unexpected activity in MyCloud audit logs while the account owner remains actively logged in from a known device.
Detection Strategies
- Correlate MyCloud authentication logs to identify overlapping session windows for the same user identity.
- Build alerts for impossible-travel patterns and simultaneous logins from distinct ASN or device fingerprints.
- Baseline normal session counts per user and flag deviations exceeding expected concurrency thresholds.
Monitoring Recommendations
- Forward MyCloud authentication and session events to a centralized SIEM or data lake for retention and correlation.
- Enable alerting on repeated failed logins followed by successful authentication from a new source.
- Review privileged account session activity daily and validate any concurrent sessions with the account owner.
How to Mitigate CVE-2026-56583
Immediate Actions Required
- Consult the HCL Software Knowledge Base Article and apply the vendor-recommended remediation for HCL MyCloud.
- Enforce multi-factor authentication (MFA) for all MyCloud accounts to reduce the value of stolen credentials.
- Rotate credentials for high-value or privileged accounts and audit recent session activity.
Patch Information
HCL has published remediation guidance in KB0132381. Administrators should review the knowledge base article to confirm fixed versions and required configuration changes, then apply updates during a scheduled maintenance window. Validate remediation by attempting concurrent logins from separate clients and confirming that prior sessions are invalidated.
Workarounds
- Configure shorter session timeouts and idle expiration windows where the product allows.
- Restrict MyCloud access to trusted network ranges or via a VPN and identity-aware proxy.
- Educate users to log out of unused sessions and to report unexpected session activity immediately.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
