CVE-2021-27893
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 · uneditedSSH Tectia Client and Server before 6.4.19 on Windows allow local privilege escalation in nonstandard conditions. ConnectSecure on Windows is affected.
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 · moderate confidenceLocal privilege escalation vulnerability in SSH Tectia Client and Server for Windows versions prior to 6.4.19, also affecting ConnectSecure on Windows. Exploitation requires specific nonstandard conditions to be present on the target 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< 6.4.19all versions< 6.4.19CVSS 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
- High
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:H/PR:L/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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Check if SSH Tectia is installedOpen Windows Control Panel and view installed programs, looking for 'SSH Tectia Client', 'SSH Tectia Server', or 'SSH Tectia ConnectSecure'. Alternatively, check Program Files directory for SSH Tectia installation folders.Affected if Any of these three products appear in the installed programs list
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Determine installed versionLocate the SSH Tectia installation directory (typically in Program Files or Program Files (x86)), then right-click the main executable (such as ssh-tectia-client.exe or ssh-tectia-server.exe), select Properties, and view the Version tab. Or use PowerShell: Get-ItemProperty 'HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*' | Where-Object {$_.DisplayName -like '*SSH Tectia*'} | Select-Object DisplayName, DisplayVersionAffected if The displayed version is lower than 6.4.19, or for ConnectSecure any version is shown (all versions are affected)
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Check for nonstandard configuration conditionsExamine the SSH Tectia configuration files in the installation directory for non-standard settings. Look for configuration files with elevated permissions or unusual service account assignments. Review the service configuration in Windows Services (services.msc) for the SSH Tectia service to identify if it runs under a privileged account with nonstandard permissions.Affected if The SSH Tectia service is configured with unusual permissions, runs under a highly privileged account, or configuration files have improper access controls that allow modification by lower-privileged users
A user is affected if SSH Tectia Client, Server, or ConnectSecure is installed with a version below 6.4.19 (or any version of ConnectSecure) AND nonstandard configuration conditions exist on the system that enable privilege escalation.
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 data6.4.19
Upgrade to SSH Tectia/ConnectSecure version 6.4.19 or later. Investigate and remediate the specific nonstandard configuration conditions that enable the privilege escalation.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-27893 — 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-2021-27893 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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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