CVE-2026-39890
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 · uneditedPraisonAI is a multi-agent teams system. Prior to 4.5.115, the AgentService.loadAgentFromFile method uses the js-yaml library to parse YAML files without disabling dangerous tags (such as !!js/function and !!js/undefined). This allows an attacker to craft a malicious YAML file that, when parsed, executes arbitrary JavaScript code. An attacker can exploit this vulnerability by uploading a malicious agent definition file via the API endpoint, leading to remote code execution (RCE) on the server. This vulnerability is fixed in 4.5.115.
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 confidenceThe AgentService.loadAgentFromFile method in PraisonAI uses the js-yaml library to parse YAML files without disabling dangerous YAML tags (!!js/function and !!js/undefined). These tags allow arbitrary JavaScript code to be deserialized and executed during YAML parsing. An attacker can exploit this by uploading a malicious agent definition file through an API endpoint, achieving remote code execution 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<= 4.5.114CVSS 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 installed PraisonAI versionRun 'pip show praisonai' or check package.json to find the installed version numberAffected if Version is 4.5.114 or lower
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Locate AgentService.loadAgentFromFile usageSearch codebase for 'loadAgentFromFile' method calls in the AgentService moduleAffected if The method is present and actively used in the application
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Inspect YAML parsing configurationExamine the js-yaml parser initialization in loadAgentFromFile - look for whether 'unsafe' or '!!js/function' tags are enabledAffected if YAML parsing uses unsafe loading that allows !!js/function or !!js/undefined tags
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Verify API endpoint accessibilityCheck if the agent file upload API endpoint exists and is exposed (typically /api/agents/upload or similar path)Affected if The upload endpoint is accessible without proper validation
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Check for recent malicious agent filesReview uploaded agent YAML files in the application's agent definitions directory for suspicious !!js/function or !!js/undefined tagsAffected if Any agent definition files contain the dangerous YAML tags
Environment is affected if PraisonAI version is 4.5.114 or lower AND the application uses the loadAgentFromFile method with js-yaml that has not disabled dangerous deserialization tags.
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 · scopedUpgrade to PraisonAI version 4.5.115 or later which properly disables dangerous YAML tags during parsing. If immediate upgrade is not feasible, restrict API endpoint access and implement file upload validation.
4.5.115
- 1. Check current PraisonAI version using: pip show praisonai or pip list | grep praisonai
- 2. Upgrade to the fixed version 4.5.115 using: pip install praisonai==4.5.115
- 3. Verify the upgrade was successful by running: pip show praisonai and confirming the version is 4.5.115
- 4. Restart any running PraisonAI services to ensure the patched version is loaded
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-39890 — 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-2026-39890 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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