dbcve.org
AndroidOperating system · Google

CVE-2021-0935

MEDIUM · 6.7 CVSS v3.1 Published 2021-10-25
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
69/100
Remediation priority · Elevated
Zero-click

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 ip6_xmit of ip6_output.c, there is a possible out of bounds write due to a use after free. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-168607263References: Upstream kernel

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

A use-after-free vulnerability in the ip6_xmit function of the Android kernel's IPv6 output code allows an attacker with System-level privileges to trigger an out-of-bounds write, potentially achieving local privilege escalation to full root access.

MitigationApply the upstream Linux kernel patch for this vulnerability through an Android system update from the device OEM, or rebuild the custom kernel with the corrected ip6_output.c code.

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:all versions

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
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/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 kernel version
    Run 'uname -r' or 'cat /proc/version' to obtain the running kernel version string
    Affected if The kernel version is unpatched and earlier than the version containing the CVE-2021-0935 fix in the ip6_xmit function
  2. Verify IPv6 kernel module is loaded
    Run 'lsmod | grep ipv6' or check /proc/net/if_inet6 to see if IPv6 networking is active
    Affected if IPv6 is enabled in the kernel, as the vulnerability exists in the ip6_xmit IPv6 output path
  3. Confirm system privileges held
    Identify if the device runs with elevated system-level privileges by checking process ownership or SELinux context via 'ps -Z' or 'id'
    Affected if The device grants System-level privileges to any process, as an attacker needs these privileges to trigger the use-after-free in ip6_xmit
  4. Check for security patch level
    Run 'getprop ro.build.version.security_patch' on Android to retrieve the last security update date
    Affected if The security patch level is earlier than the November 2021 Android security bulletin that addressed CVE-2021-0935

A defender is affected if their Android kernel lacks the CVE-2021-0935 patch, IPv6 is enabled, and the device runs with System-level privileges accessible to an attacker.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the upstream Linux kernel patch for this vulnerability through an Android system update from the device OEM, or rebuild the custom kernel with the corrected ip6_output.c code.

Recommended fix Moderate confidence

Apply the Android Security Bulletin patch for the month CVE-2021-0935 was fixed (refer to Android Security Bulletin for specific patch level)

  1. 1. Check the Android Security Bulletin for the month this vulnerability was addressed to identify the specific patch level containing the fix
  2. 2. Navigate to source.android.com/security/bulletin to find the applicable Android Security Bulletin
  3. 3. Identify the kernel patch or security patch level (SPL) that addresses this vulnerability
  4. 4. Apply the monthly security update for your Android device that includes the fix for A-168607263
  5. 5. If your device is no longer receiving security updates, consider upgrading to a device that currently receives security updates
Caveat Applying security updates may require device reboot; ensure compatibility with your device model and carrier before updating

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Android Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing24.0 h
  • Review / QA8.0 h
52.0 hours of engineering $8,720
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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-2021-0935 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