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Linux KernelOperating system · Linux

CVE-2018-20509

MEDIUM · 5.5 CVSS v3.0 Published 2019-04-30
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
57/100
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
The print_binder_ref_olocked function in drivers/android/binder.c in the Linux kernel 4.14.90 allows local users to obtain sensitive address information by reading " ref *desc *node" lines in a debugfs file.

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

The print_binder_ref_olocked function in the Linux kernel's Android binder driver (4.14.90) exposes sensitive kernel memory addresses through debugfs output. Local users can read 'ref *desc *node' lines in the debugfs file to obtain pointer values, aiding in exploitation of other kernel vulnerabilities.

MitigationRestrict debugfs access to privileged users or apply the kernel security patch that removes address information from the binder debugfs output.

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
Linux KernelOperating system
Affected:= 4.14.90

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

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

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 kernel version
    Run 'uname -r' to see the running kernel version
    Affected if Version is exactly 4.14.90 (only this specific version is affected)
  2. Verify debugfs is mounted
    Run 'mount | grep debugfs' to see if debugfs is currently mounted
    Affected if debugfs is mounted and readable by unprivileged users
  3. Check for binder debugfs entries
    List contents of /sys/kernel/debug/binder/ (or /d/binder/ if debugfs is mounted elsewhere) using 'ls -la'
    Affected if Binder debugfs directory exists and contains 'ref *desc *node' files readable by non-root users
  4. Inspect binder debugfs output for addresses
    Read files in the binder debugfs directory (e.g., 'cat /sys/kernel/debug/binder/refs/*') and look for hex pointer values in lines matching 'ref *desc *node' pattern
    Affected if Output contains kernel memory pointer addresses rather than sanitized placeholder values

You are affected if running kernel version 4.14.90 with the Android binder driver enabled and debugfs mounted with world-readable access that exposes raw pointer addresses in binder reference output.

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

Restrict debugfs access to privileged users or apply the kernel security patch that removes address information from the binder debugfs output.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2018-20509 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