CVE-2018-9431 is a high severity improper input validation, tagged by NVD as an incorrect default permissions weakness in the OSUInfo class (OSUInfo.java). NVD scores it 7.8. Google fixes it at security patch level 2018-07-05 or later. Install the device update that reaches that level.
What's affected
- Product: Android, in the OSUInfo class (OSUInfo.java).
- Releases listed by the bulletin: 8.0 and 8.1. The NVD product list shows only some Android releases, so treat the bulletin as the fuller list.
- Fixed in: security patch level 2018-07-05 or later, according to the Pixel and Nexus Security Bulletin for July 2018.
- Impact in the record: local escalation of privilege with no extra privileges and no user interaction.
- Severity: NVD scores it 7.8 High (vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H). The bulletin lists it as Moderate, type EoP. Both ratings are given because they differ.
- Weakness classes: CWE-276 (Incorrect Default Permissions).
How to check if you're exposed
- On the device, open Settings and find the Android security patch level, usually under About phone. The exact path varies by manufacturer. A date earlier than 2018-07-05 means the fix is not present.
- With a USB debugging connection, run
adb shell getprop ro.build.version.security_patch. It prints the patch level as a date. You need 2018-07-05 or later. - For a fleet, export the patch level from your mobile device management console and filter for dates earlier than 2018-07-05.
- Match each device against the release list above. Devices on releases outside it are not named for this CVE, but check them against the other entries in the same bulletin.
What to do now
- Identify every Android device in scope and record its current security patch level.
- Roll out the manufacturer or carrier update that reaches 2018-07-05 or later. Google publishes the fixes, but each device maker decides when its devices receive them.
- For devices that no longer receive updates, plan replacement or limit what they can reach, such as corporate mail and internal apps.
- Write the update policy down, with a maximum patch age, and report exceptions.
Why it matters
Only Android 8.0 and 8.1 are listed. The record text says improper input validation, while the weakness tag is CWE-276, so the two descriptions are not perfectly aligned. The bulletin remains the reference for what was changed.
Input validation errors in privileged system code let a less privileged caller shape data that the system then trusts. When the trust boundary is a permission, the result is a privilege gain. The fix tightens what the class accepts. The record's KEV flag is false, so CISA does not list it as exploited. That is the absence of a report in the sources read, not proof that no one has tried.
Quick check
The description and the weakness tag do not match. Which is right?
The description says improper input validation and the NVD weakness tag is CWE-276, incorrect default permissions. Both appear in the record. The bulletin is the better source for the exact change, and the fix is the same either way.
Which patch level should I look for?
The Pixel and Nexus Security Bulletin for July 2018 places this fix at 2018-07-05. Any date at or after 2018-07-05 includes it. Some makers ship it under a different update name, so check the date.
Sources
- Pixel and Nexus Security Bulletin for July 2018: Affected releases, severity, type and the patch level that carries the fix.
Last reviewed: 19 October 2026.
