CVE-2021-26828
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 · uneditedOpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows remote authenticated users to upload and execute arbitrary JSP files via view_edit.shtm.
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 confidenceThis is an authenticated file upload vulnerability in OpenPLC ScadaBR where the view_edit.shtm endpoint allows remote authenticated users to upload and execute arbitrary JSP files, leading to remote code execution. An attacker with valid credentials can upload a malicious JSP web shell and execute commands on the server.
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<= 0.9.1<= 1.12.4CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/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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Identify ScadaBR installationLook for ScadaBR web application files in common paths: on Linux check /opt/ScadaBR, /var/lib/tomcat*/webapps/ScadaBR, or /opt/OpenPLC_v3/scadaBR; on Windows check C:\ScadaBR or Tomcat webapps directories. Also check for running services on ports 8080 or 8443.Affected if ScadaBR is not installed - the system is not affected by this vulnerability.
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Determine ScadaBR versionLocate the version file or check the application about page: on Linux examine /opt/ScadaBR/WEB-INF/classes/com/scadabr/version.properties or the ScadaBR About page via web interface at http://<host>:8080/ScadaBR/about.shtmAffected if The installed version is 0.9.1 (Linux) or 1.12.4 (Windows) or earlier - these versions contain the vulnerable endpoint.
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Verify view_edit.shtm endpoint existsCheck if the file view_edit.shtm exists in the ScadaBR web directory: on Linux at /opt/ScadaBR/web/WEB-INF/view/view_edit.shtm or similar path under the webapp root; on Windows check the corresponding path under the Tomcat webapps folder.Affected if The file view_edit.shtm exists - the vulnerable upload endpoint is present in the application.
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Check authentication requirementAttempt to access the endpoint without credentials: send a GET request to http://<host>:8080/ScadaBR/view_edit.shtm. If it redirects to a login page, authentication is required; if it responds directly, the endpoint may be exposed.Affected if The endpoint is accessible without authentication or uses weak authentication - exploitation is easier. However, even with authentication required, an authenticated user can still exploit the vulnerability.
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Inspect upload directory permissionsCheck the upload directory configuration in the ScadaBR web.xml or application properties files. Look for paths where file uploads are stored and verify if JSP execution is permitted in those directories.Affected if The upload directory allows JSP file execution (no restrictions in web.xml or .htaccess equivalent) - successful exploitation leads to remote code execution.
A system is affected if ScadaBR versions 0.9.1 or 1.12.4 or earlier are installed and the view_edit.shtm endpoint is accessible to authenticated users, with the upload directory permitting JSP execution.
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 dataRestrict and validate file uploads in view_edit.shtm by implementing strict allowlist-based file type validation, removing executable permissions from upload directories, and applying vendor patches. If patches are unavailable, disable the file upload functionality or restrict access to trusted users only.
- Consultation3.0 h
- Implementation6.0 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-2021-26828 — 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-2021-26828 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
- No weaponised exploit code, or anything meant to cause harm
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