CVE-2018-20187
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 · uneditedA side-channel issue was discovered in Botan before 2.9.0. An attacker capable of precisely measuring the time taken for ECC key generation may be able to derive information about the high bits of the secret key, as the function to derive the public point from the secret scalar uses an unblinded Montgomery ladder whose loop iteration count depends on the bitlength of the secret. This issue affects only key generation, not ECDSA signatures or ECDH key agreement.
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 confidenceA timing side-channel vulnerability in Botan before 2.9.0 allows attackers to derive information about the high bits of ECC secret keys. The issue is in ECC key generation where the Montgomery ladder implementation used to derive the public point from the secret scalar is unblinded, causing loop iteration count to depend on the bitlength of the secret key. Precise timing measurements can leak this information.
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< 2.9.0CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.0/AV:N/AC:H/PR:N/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 checksWork through these to decide whether this CVE applies to you.
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Locate the Botan library installationIdentify where the Botan library is installed on your system; common locations include system library directories (/usr/lib, /usr/local/lib) or package-managed locationsAffected if Botan library files are present on the system
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Determine the installed Botan versionUse the system's package manager (dpkg, rpm, brew) or check the library file version metadata; alternatively, run 'botan --version' if the CLI tool is installedAffected if Unable to determine a version number or version appears to be missing
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Compare version against the affected rangeCheck if the installed version is semantically less than 2.9.0 (for example, 2.8.0, 2.7.0, 2.6.0, 1.11, etc.)Affected if The installed version is a release prior to 2.9.0 (e.g., 2.8.0, 2.7.0, or any 1.x release)
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Identify ECC key generation usageReview application logs or code that uses Botan for ECC key generation operations; note that this vulnerability affects only key generation, not ECDSA signing or ECDH key exchangeAffected if Applications use Botan to generate ECC keys and the library version is below 2.9.0
Your environment is affected if the installed Botan library version is lower than 2.9.0 and you use it for ECC key generation.
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 data2.9.0
Upgrade to Botan 2.9.0 or later which implements proper blinding in the Montgomery ladder for ECC key generation. This affects only key generation, not ECDSA signatures or ECDH key agreement.
- Consultation4.0 h
- Implementation2.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-20187 — 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-2018-20187 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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- Version or environment caveats, and links to real fixes
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