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CVE-2025-62631 is an insufficient session expiration vulnerability (CWE-613) in Fortinet FortiOS affecting versions 7.4.0, 7.2 all versions, 7.0 all versions, and 6.4 all versions. The flaw occurs in the SSLVPN session management mechanism where session tokens are not properly invalidated after a user changes their password. Normally, password changes should trigger immediate session termination to prevent unauthorized access, but due to this vulnerability, active SSLVPN sessions remain valid under specific conditions outside an attacker’s control. This inconsistency arises from improper handling of session expiration events tied to credential updates. When a password is changed, the system fails to revoke existing session identifiers, allowing persistent access. Attackers who have compromised an active session—for example, through phishing or credential theft—can thus maintain network access even after the legitimate user changes their password. The vulnerability likely stems from a race condition or misconfiguration in session cleanup routines, where session databases are not updated synchronously with authentication changes. This bypasses security measures that rely on session termination for credential rotation. Exploitation requires an existing active session, but once established, attackers can avoid detection by leveraging the lingering session. The conditions for exploitation are not publicly detailed but may involve specific timing or system states during password updates. This flaw highlights critical gaps in session lifecycle management within FortiOS’s SSLVPN implementation, emphasizing the need for robust session validation. It allows attackers to sustain access without needing the new password, leading to potential data breaches, lateral movement, and network compromise. Mitigation involves patching or workarounds to enforce session invalidation.
Platform: Fortinet FortiOS
Version: 7.4.0,7.2,7.0,6.4
Vulnerability: Insufficient session expiration
Severity: Medium
Date: 12/09/2025
Prediction: Patch TBA
What Undercode Say:
Check active SSLVPN sessions
show vpn sslvpn session
Monitor session logs
grep “SSLVPN” /var/log/fortios.log
Detect vulnerable versions
fortios_version=$(ssh admin@fortigate show system status | grep Version)
Test session persistence
curl -k –cookie “sessionid=active” https://fortigate/vpn
List running processes
ps aux | grep sslvpnd
Analyze network connections
netstat -tpn | grep 443
Extract session tokens
tcpdump -i any port 443 -A
Force password change
echo “change password” | ssh admin@fortigate
Session timeout check
cat /proc/$(pidof sslvpnd)/status
How Exploit:
Attacker maintains active SSLVPN session after password change using valid session tokens. No re-authentication required. Session hijacking or credential theft initially. Exploits flawed session invalidation.
Protection from this CVE:
Apply Fortinet patches. Enforce session termination on password change. Use multi-factor authentication. Monitor active sessions regularly. Implement network segmentation.
Impact:
Unauthorized persistent network access. Data exfiltration risk. Compliance violations. Lateral movement potential. Affects confidentiality and integrity.
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Sources:
Reported By: nvd.nist.gov
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