CVE-2019-12953
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 · uneditedDropbear 2011.54 through 2018.76 has an inconsistent failure delay that may lead to revealing valid usernames, a different issue than CVE-2018-15599.
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 confidenceDropbear SSH versions 2011.54 through 2018.76 contains a timing side-channel during authentication where the server responds with inconsistent delays for invalid usernames versus valid but incorrect passwords. Attackers can exploit this timing difference to enumerate valid usernames on the system.
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>= 2011.54, <= 2018.76CVSS 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
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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.
-
Check if Dropbear SSH is installedRun 'which dropbear' or 'which dropbearkey' to locate the Dropbear binaries. Also check for running processes with 'ps aux | grep dropbear'.Affected if No Dropbear SSH binary is found on the system.
-
Identify the installed Dropbear SSH versionRun 'dropbear -V' or 'dropbearkey -V' to display the version number. If the binary is not in PATH, locate it first using 'find / -name dropbear -type f 2>/dev/null' and then run the version command.Affected if Unable to retrieve the version number from the Dropbear installation.
-
Compare the version against the affected rangeVerify that the installed version falls within >= 2011.54 and <= 2018.76. Compare the full version string (e.g., 2018.76) numerically.Affected if The installed version is 2011.54 or higher but 2018.76 or lower.
-
Confirm the vulnerability applies to this installationThis CVE affects Dropbear SSH when the SSH service is running and accepting authentication attempts. The timing side-channel exists in the authentication path for valid users versus invalid usernames.Affected if Dropbear SSH version is within the affected range AND the service is running and accessible for authentication.
A user is affected if Dropbear SSH version 2011.54 through 2018.76 is installed and the SSH service is operational and accepting connections.
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 dataUpgrade Dropbear SSH to a version beyond 2018.76 (latest stable release) to obtain the patch that enforces consistent failure response timing regardless of username validity.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-12953 — 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-2019-12953 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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