CVE-2021-42857
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 · uneditedIt was discovered that the SteelCentral AppInternals Dynamic Sampling Agent's (DSA) AgentDaServlet has directory traversal vulnerabilities at the "/api/appInternals/1.0/agent/da/pcf" API. The affected endpoint does not have any validation of the user's input that allows a malicious payload to be injected.
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 confidenceA directory traversal vulnerability exists in SteelCentral AppInternals Dynamic Sampling Agent's AgentDaServlet at the /api/appInternals/1.0/agent/da/pcf API endpoint. The affected endpoint fails to validate user-supplied input, allowing attackers to inject path traversal sequences (e.g., ../../../) to access files outside the web root.
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>= 11.0.0, < 11.8.8>= 12.0.0, < 12.13.0= 10.0.0CVSS 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
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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 the SteelCentral AppInternals Dynamic Sampling Agent versionLocate the agent installation directory and check the version file or use the agent's version command if available. Common locations include the installation path where the agent was deployed.Affected if The installed version falls within these ranges: 10.0.0, or >= 11.0.0 but < 11.8.8, or >= 12.0.0 but < 12.13.0
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Verify the AgentDaServlet endpoint is accessibleAttempt to access the /api/appInternals/1.0/agent/da/pcf endpoint on the host running the Dynamic Sampling Agent. This may require network access to the agent's web service port.Affected if The endpoint responds with any HTTP status (including 404 or error pages), indicating the vulnerable API is exposed
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Confirm the agent web interface does not require authenticationAttempt to access the affected API endpoint without providing credentials. Observe whether the request is processed or rejected due to authentication requirements.Affected if The endpoint processes requests without requiring authentication, meaning any unauthenticated user could exploit the path traversal vulnerability
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Check if path traversal characters are accepted in the APISend a test request to the /api/appInternals/1.0/agent/da/pcf endpoint with path traversal sequences (such as ../) as part of the request parameters or body, and observe whether the application accepts and processes them.Affected if The application accepts and processes path traversal sequences without rejecting or sanitizing them, allowing access to files outside the web root
You are affected if the SteelCentral AppInternals Dynamic Sampling Agent version is 10.0.0, between 11.0.0 and 11.8.8 (exclusive), or between 12.0.0 and 12.13.0 (exclusive), AND the /api/appInternals/1.0/agent/da/pcf endpoint is accessible and accepts unauthenticated requests with path traversal sequences.
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 · scoped11.8.812.13.0
Implement strict input validation and sanitization on the affected endpoint to reject path traversal sequences. Additionally, apply principle of least privilege to file system access and consider restricting the API to authenticated users only.
Version 11.8.8 or later for the 11.x branch; Version 12.13.0 or later for the 12.x branch
- Identify the current version of SteelCentral AppInternals Dynamic Sampling Agent running in your environment
- If running version 10.0.0, upgrade to version 11.8.8 or later (or 12.13.0 or later for the latest branch)
- If running version >= 11.0.0 and < 11.8.8, upgrade to version 11.8.8 or later
- If running version >= 12.0.0 and < 12.13.0, upgrade to version 12.13.0 or later
- Obtain the appropriate installer from the vendor support portal (aternity.force.com)
- Follow vendor documentation to install the upgrade, ensuring to back up configuration data first
- After upgrade, verify the /api/appInternals/1.0/agent/da/pcf endpoint now properly validates input and rejects directory traversal attempts
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2021-42857 — 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-2021-42857 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
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