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AndroidOperating system · Google

CVE-2021-0393

HIGH · 7.8 CVSS v3.1 Published 2021-03-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
81/100
Remediation priority · High
No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In Scanner::LiteralBuffer::NewCapacity of scanner.cc, there is a possible out of bounds write due to an integer overflow. This could lead to remote code execution if an attacker can supply a malicious PAC file, with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11 Android-8.1 Android-9 Android-10Android ID: A-168041375

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In Android's Scanner::LiteralBuffer::NewCapacity function within scanner.cc, an integer overflow allows an attacker to write beyond buffer boundaries when processing a malicious PAC (Proxy Auto-Config) file. This memory corruption can be leveraged for remote code execution without any user interaction, affecting Android versions 8.1 through 11.

MitigationApply the Android security patch level for the affected month (referenced by Android ID A-168041375) to vulnerable devices. Until patches are applied, block or validate PAC files from untrusted network sources.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
AndroidOperating system
Affected:= 8.1= 9.0= 10.0= 11.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Android version
    Navigate to Settings > About Phone and verify the Android version is 8.1, 9.0, 10.0, or 11.0. Alternatively, run `getprop ro.build.version.release` via ADB shell.
    Affected if The device runs Android 8.1, 9.0, 10.0, or 11.0 and has not received the security patch for the month containing Android ID A-168041375
  2. Identify PAC file support
    Determine if the device uses Android's built-in networking stack that supports Proxy Auto-Config (PAC) files. PAC support is typically found in system network settings under Settings > Network & Internet > Mobile Network > Access Point Names or Settings > Wi-Fi > Saved Networks.
    Affected if The device has PAC file functionality present in the system networking components
  3. Check for active PAC configuration
    Inspect whether a PAC script is configured on the device. On Android, this can be found in Settings under Wi-Fi networks (long press a network > Modify network > Advanced options > Proxy) or in Settings > Network & Internet > Mobile Network > Access Point Names. Run `settings get global http_proxy` via ADB shell to check for an active PAC URL.
    Affected if A PAC script URL is actively configured on the device, meaning the vulnerable code path would be exercised when network connections are made
  4. Verify security patch level
    Navigate to Settings > About Phone > Android security patch level to confirm whether the device has received the patch for the month referencing Android ID A-168041375. Alternatively, run `getprop ro.build.version.security_patch` via ADB shell.
    Affected if The security patch level is earlier than the patch that addresses A-168041375 (the specific month varies by device OEM)

The device is affected if it runs Android 8.1 through 11.0 with an unpatched security level and has PAC file processing enabled or configured on the system.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Android security patch level for the affected month (referenced by Android ID A-168041375) to vulnerable devices. Until patches are applied, block or validate PAC files from untrusted network sources.

Fix this in Android Scoped from the published advisory
  • Consultation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
8.0 hours of engineering $1,360
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-0393 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data