CVE-2018-21058
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 · uneditedAn issue was discovered on Samsung mobile devices with N(7.0), O(8.0) (exynos7420 or Exynos 8890/8996 chipsets) software. Cache attacks can occur against the Keymaster AES-GCM implementation because T-Tables are used; the Cryptography Extension (CE) is not used. The Samsung ID is SVE-2018-12761 (September 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 · high confidenceThe Keymaster AES-GCM implementation on Samsung mobile devices with N(7.0) and O(8.0) software uses software-based T-Table lookups instead of hardware Cryptography Extension (CE), enabling cache timing side-channel attacks that can potentially recover cryptographic keys.
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= 7.0= 8.0CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Verify the device manufacturer is SamsungCheck the device settings or use 'getprop ro.product.manufacturer' command in ADB shell to confirm the device is from SamsungAffected if The device is not manufactured by Samsung, this specific vulnerability does not apply
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Check the Android versionUse 'getprop ro.build.version.release' in ADB shell or check Settings > About Phone > Android version. Confirm the version is exactly 7.0 (Nougat) or 8.0 (Oreo)Affected if The Android version is not 7.0 or 8.0, the device is not in the affected version range for this CVE
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Confirm Keymaster implementation uses T-Table AES-GCMExamine the Keymaster TA logs or firmware version. On affected Samsung devices, the Keymaster version will indicate software-based crypto implementation. This typically requires access to Samsung-specific diagnostic tools or reviewing the Samsung security bulletin for the device modelAffected if The Keymaster implementation has been updated to use hardware Cryptography Extension (CE) or constant-time implementation, the device is not vulnerable to the timing side-channel attack described
A Samsung mobile device running Android 7.0 or 8.0 with Keymaster still using software-based T-Table AES-GCM implementation is affected by this CVE.
Generated from the published advisory. Verify against your own configuration.
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 dataSamsung firmware update required to replace T-Table-based AES-GCM with constant-time implementation or enable hardware CE. Users should apply September 2018 security patches.
- Consultation12.0 h
- Implementation80.0 h
- Testing24.0 h
- Review / QA16.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-21058 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2018-21058 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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