dbcve.org
AndroidOperating system · Google

CVE-2018-21065

CRITICAL · 9.8 CVSS v3.1 Published 2020-04-08
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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
An issue was discovered on Samsung mobile devices with M(6.0), N(7.x), and O(8.x) software. There is an integer underflow in eCryptFS because of a missing size check. The Samsung ID is SVE-2017-11855 (August 2018).

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 · moderate confidence

An integer underflow vulnerability exists in the eCryptFS filesystem implementation on Samsung mobile devices running Android M(6.0), N(7.x), and O(8.x). The flaw stems from a missing size check, allowing an attacker to trigger an underflow condition that could corrupt memory or potentially enable code execution in the kernel context where eCryptFS operates.

MitigationOrganizations should identify all affected Samsung devices within their fleet and apply available firmware updates from Samsung's security patch releases. Until patches are available, restrict access to untrusted storage media and monitor for indicators of compromise targeting the filesystem layer.

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:= 6.0= 7.0= 7.1.0= 7.1.1= 7.1.2= 8.0= 8.1

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/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. Identify the device manufacturer
    Check the device info to confirm it is a Samsung mobile device (e.g., via Settings > About Phone > Manufacturer or model number)
    Affected if The device is not manufactured by Samsung, then this specific CVE does not apply
  2. Check the Android version
    Navigate to Settings > About Phone > Android version, or run 'getprop ro.build.version.release' via ADB shell
    Affected if The Android version is 6.0, 7.0, 7.1.0, 7.1.1, 7.1.2, 8.0, or 8.1 - if it matches any of these exact versions, the device falls within the affected range
  3. Verify eCryptFS filesystem is in use
    Check if eCryptFS is mounted or active on the device by examining mount output (run 'mount' command via ADB shell) or check for eCryptFS-related processes or kernel modules
    Affected if eCryptFS is actively mounted or being used as the encrypted filesystem layer on the device - the vulnerability only applies when eCryptFS is enabled and operating
  4. Confirm the kernel supports eCryptFS
    Check the kernel configuration or loaded modules for eCryptFS support (look for 'ecryptfs' in /proc/filesystems or check kernel module listing via 'lsmod' via ADB shell)
    Affected if The kernel has eCryptFS compiled in or loaded as a module, and the device meets the version criteria above

A device is affected if it is a Samsung mobile device running Android 6.0, 7.0, 7.1.0, 7.1.1, 7.1.2, 8.0, or 8.1, AND the eCryptFS filesystem is actively mounted or operational on that device.

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

Organizations should identify all affected Samsung devices within their fleet and apply available firmware updates from Samsung's security patch releases. Until patches are available, restrict access to untrusted storage media and monitor for indicators of compromise targeting the filesystem layer.

Recommended fix High confidence

Samsung August 2018 security patch or later (SVE-2017-11855)

  1. Check your Samsung device's current Android version by going to Settings > About Phone
  2. Navigate to Settings > Software Update and download/install the latest Samsung security patch
  3. Alternatively, manually check for updates or contact your carrier for the August 2018 Samsung security update or later
  4. Verify the security patch level in Settings > About Phone > Software Information after updating
Caveat Users should back up important data before applying system updates as a general precaution

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

Fix this in Android Scoped from the published advisory
  • Consultation8.0 h
  • Implementation4.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,840
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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-2018-21065 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