CVE-2021-26605
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 improper input validation vulnerability in the service of ezPDFReader allows attacker to execute arbitrary command. This issue occurred when the ezPDF launcher received and executed crafted input values through JSON-RPC communication.
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 confidenceCVE-2021-26605 is a critical command injection vulnerability in ezPDFReader's service component. The ezPDF launcher accepts input through JSON-RPC communication and executes commands without proper input validation, allowing attackers to inject and execute arbitrary system commands.
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>= 2.0, <= 3.0CVSS 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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Identify if ezPDFReader is installedSearch for ezPDFReader or Unidocs Ezpdfreader software on the system. Check installed programs list, application directories, or service listings for 'ezpdf', 'ezPDF', or 'unidocs'.Affected if The software is present on the system
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Determine the installed versionLocate the ezPDFReader application and retrieve its version information. This may be found in the application's properties, about dialog, or version file within the installation directory.Affected if The version falls within the range >= 2.0 and <= 3.0
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Verify the JSON-RPC service component is enabledCheck if the ezPDF service component that handles JSON-RPC communication is running or available. Look for processes or services related to ezPDF launcher or PDF service that accept JSON-RPC requests.Affected if The JSON-RPC service component is active or accessible on the system
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Check network exposure of the serviceExamine network configuration to determine if the JSON-RPC service is bound to network interfaces. Review firewall rules and listening ports to see if the service accepts remote connections.Affected if The JSON-RPC service is exposed to network access (especially untrusted networks)
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Inspect for suspicious command execution activityReview system logs, application logs, and command history for unusual or unauthorized commands that may have originated from ezPDFReader processes. Look for unexpected system calls or process executions.Affected if Evidence of arbitrary command execution or injection attempts is found in logs
A system is affected by CVE-2021-26605 if Unidocs Ezpdfreader version 2.0 through 3.0 is installed and the JSON-RPC service component is enabled and 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.
From vendor dataImplement strict input validation and sanitization on all JSON-RPC request parameters before passing them to any command execution functions. Consider using parameterized approaches or whitelist validation instead of directly incorporating user input into system calls.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-26605 — 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-2021-26605 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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