CVE-2021-31635
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 · uneditedServer-Side Template Injection (SSTI) vulnerability in jFinal v.4.9.08 allows a remote attacker to execute arbitrary code via the template function.
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 confidenceServer-Side Template Injection (SSTI) vulnerability in jFinal framework version 4.9.08 allows remote attackers to inject malicious template expressions that are evaluated by the server's template engine, leading to arbitrary code execution. The vulnerability stems from insufficient sanitization of user-supplied input when processing template functions.
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= 4.9.08CVSS 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 jFinal framework versionInspect your project's dependency configuration (pom.xml, build.gradle, or similar build file) or the jFinal JAR file in your lib directory to locate the exact version of jFinal being usedAffected if The jFinal version is 4.9.08
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Locate template rendering code pathsSearch your codebase for usages of jFinal's template engine classes or methods that process templates - look for patterns like Template.render() or similar template execution callsAffected if Your application uses jFinal's template rendering feature to process templates
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Inspect input handling to templatesReview the code that passes data to the template engine - trace how request parameters or user data flow into template rendering callsAffected if User-supplied input (request parameters, headers, or other user-controlled data) is passed directly to the template engine without sanitization or validation
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Review template configurationCheck your jFinal configuration class for template engine setup - examine any custom template configuration or sandbox settingsAffected if No input validation, sandboxing, or sanitization is implemented for template rendering
You are affected if running jFinal 4.9.08 and your application passes unsanitized user input to the template engine.
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 dataUpgrade jFinal to a patched version (if available) or implement input validation/sandboxing for template rendering. If upgrading is not feasible, restrict or disable the vulnerable template functionality and review all template rendering code paths.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-31635 — 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-2021-31635 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
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