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How the CVE Works:
The vulnerability exists within the `startAlwaysOnVpn` method of `Vpn.java` in the Android framework. A flawed logical condition prevents the correct enforcement of the always-on VPN policy. When a device attempts to establish or manage its always-on VPN connection, this logic error can be triggered, causing the system to incorrectly deem the VPN as unavailable or disabled. This flaw allows a local, unprivileged application or process to programmatically induce a state where the mandatory VPN tunnel is deactivated. Since the vulnerability resides in a core system service, exploitation does not require user interaction or special permissions, enabling a local attacker to bypass critical network security boundaries and potentially intercept or manipulate device traffic.
DailyCVE Form:
Platform: Android
Version: Framework
Vulnerability: VPN Bypass
Severity: Critical
Date: 2025-12-08
Prediction: Patch 2025-12-15
What Undercode Say:
adb shell dumpsys connectivity | grep AlwaysOnVpn adb logcat | grep -i vpn | grep -i error
// Pseudo-code reflecting the flawed logic
if (someCondition || otherCondition) {
// Correct path: keep VPN enabled
} else {
// Flawed logic error leads here, disabling VPN
disableAlwaysOnVpn(); // This should not be reachable
}
How Exploit:
1. Attacker installs a benign-looking local app.
- The app calls specific APIs or triggers system intents that interact with the VPN service.
- It exploits the logical condition to force the `startAlwaysOnVpn` method into the erroneous code path.
- The always-on VPN policy is silently disabled, dropping the secure tunnel.
- Attacker’s app or associated process can now monitor or redirect unencrypted device traffic.
Protection from this CVE:
Apply the official Android security patch from Google when released. Restrict installation of untrusted applications. Monitor for unusual VPN disconnection events. Use endpoint detection that alerts on VPN state changes.
Impact:
Local privilege escalation. Complete bypass of forced VPN tunneling. Loss of mandatory network encryption. Potential for internal network access and data interception.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
