What’s Vulnerable › Vulnerabilities

CVE-2018-9840

• Severity: medium (CVSS 6.8 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2018-04-10 · updated 2026-06-17

Description

The Open Whisper Signal app before 2.23.2 for iOS allows physically proximate attackers to bypass the screen locker feature via certain rapid sequences of actions that include app opening, clicking on cancel, and using the home button.

Affected products

• Signal: before 2.23.2 — fixed in 2.23.2

How to fix

Upgrade to a fixed version: Signal 2.23.2. Check the vendor advisory for mitigations.

References

• http://nint.en.do/Signal-Bypass-Screen-locker.php
• https://github.com/signalapp/Signal-iOS/commit/018a35df7b42b4941cb4dfc9f462b37c3fafd9e9
• https://github.com/signalapp/Signal-iOS/commits/release/2.23.2
• http://nint.en.do/Signal-Bypass-Screen-locker.php
• https://github.com/signalapp/Signal-iOS/commit/018a35df7b42b4941cb4dfc9f462b37c3fafd9e9
• https://github.com/signalapp/Signal-iOS/commits/release/2.23.2

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