CVE-2021-39434
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 default username and password for an administrator account was discovered in ZKTeco ZKTime 10.0 through 11.1.0, builds 20180901, 20190510.1, 20200309.3, 20200930, 20201231, and 20210220.
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 default hardcoded administrator username and password was discovered in ZKTeco ZKTime time management software versions 10.0 through 11.1.0 across multiple build versions (20180901, 20190510.1, 20200309.3, 20200930, 20201231, 20210220). This allows unauthenticated remote attackers to gain full administrative access to 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>= 10.0, <= 11.1.0= 11.1.0CVSS 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
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/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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Identify if ZKTeco ZKTime is installedSearch for ZKTime installation directories (commonly in C:\Program Files\ZKTeco or C:\ZKTeco) or check for ZKTime services via Windows Services console (services.msc) or Linux equivalent process listingsAffected if ZKTime software is present on the system
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Determine installed ZKTime versionLocate the ZKTime installation and check for version information in the executable properties, About dialog within the application, or check version files in the installation directory. Common locations: right-click the ZKTime.exe file and select Properties > Details, or look for version.txt/readme.txt in the program folderAffected if Installed version falls within 10.0 through 11.1.0 inclusive, or displays build numbers 20180901, 20190510.1, 20200309.3, 20200930, 20201231, or 20210220
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Verify default administrator account statusAttempt to access the ZKTime web interface or administrative console using the default administrator credentials. Common default usernames to test include 'admin', 'administrator', or 'zkteco' (note: actual hardcoded credentials are not reproduced here for security reasons)Affected if Login succeeds with default or easily guessable administrative credentials, indicating the password has not been changed from factory defaults
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Check remote access exposureReview network configuration and firewall rules to determine if the ZKTime web interface (typically ports 80, 443, or 8080) is exposed to untrusted networks or the internet. Use netstat -an or equivalent to identify listening ports associated with ZKTimeAffected if ZKTime administrative interface is accessible from untrusted networks or the internet without VPN or IP restriction
The environment is affected if ZKTeco ZKTime versions 10.0 through 11.1.0 are installed AND the default hardcoded administrative credentials have not been changed, particularly if the service is remotely accessible.
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.
dbcve · scopedImmediately change the default administrator password to a strong, unique password on all affected ZKTime installations and ensure remote administrative access is restricted to authorized networks or disabled if not required.
Contact ZKTeco for latest version (no specific fixed version mentioned in sources)
- Immediately change the default administrator password to a strong, unique password following organizational password policies
- Locate the admin account in ZKTime settings and update the password to comply with password complexity requirements
- Verify the new password works correctly by logging out and logging back in
- Consult ZKTeco directly or check their official support channels for the latest available version and any security updates beyond 11.1.0
- Document the password change in your organization's change management system
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-39434 — 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-2021-39434 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
- No spam, self-promotion, credentials, or personal data