Platform
python
Component
praisonai
Fixed in
4.5.116
4.5.115
CVE-2026-39890 is a critical Remote Code Execution (RCE) vulnerability discovered in praisonai, a Python-based AI agent platform. This vulnerability allows attackers to execute arbitrary JavaScript code on the server by crafting malicious YAML files. The issue affects versions of praisonai up to 4.5.98, and a patch is available in version 4.5.115.
The impact of this vulnerability is severe. An attacker can exploit it by uploading a specially crafted YAML agent definition file through the API. This file, when processed by the AgentService.loadAgentFromFile method, will trigger the execution of arbitrary JavaScript code. This grants the attacker complete control over the server, enabling them to steal sensitive data, install malware, or disrupt operations. The potential blast radius is significant, as the attacker could compromise the entire system and potentially access data from connected services. This vulnerability shares similarities with other YAML deserialization vulnerabilities where unsafe tag handling leads to code execution.
CVE-2026-39890 was publicly disclosed on 2026-04-08. The vulnerability's severity is classified as CRITICAL with a CVSS score of 9.8. Currently, there are no known active exploitation campaigns targeting this vulnerability, but the availability of a public description and the ease of exploitation make it a high-priority target. The vulnerability is not currently listed on the CISA KEV catalog.
Exploit Status
EPSS
0.38% (59% percentile)
CISA SSVC
CVSS Vector
The primary mitigation for CVE-2026-39890 is to upgrade praisonai to version 4.5.115 or later, which includes the fix for this vulnerability. If upgrading immediately is not possible, consider implementing temporary workarounds. While disabling the API endpoint is an option, it severely impacts functionality. Carefully review all agent definition files before deployment, looking for suspicious YAML structures. Implement strict input validation on the API endpoint to reject files containing potentially dangerous YAML tags. After upgrading, confirm the fix by attempting to upload a known malicious YAML file and verifying that it is rejected or handled safely.
Update the js-yaml library to version 4.5.115 or higher to mitigate the vulnerability. Ensure that dangerous tags (such as `!!js/function` and `!!js/undefined`) are disabled when parsing YAML files to prevent arbitrary code execution.
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CVE-2026-39890 is a critical Remote Code Execution vulnerability in praisonai versions up to 4.5.98. It allows attackers to execute arbitrary JavaScript code by exploiting unsafe YAML deserialization.
You are affected if you are running praisonai versions 4.5.98 or earlier. Check your version and upgrade immediately.
Upgrade praisonai to version 4.5.115 or later. As a temporary workaround, review and validate all agent definition files before deployment.
While there are no confirmed active exploitation campaigns currently, the vulnerability's severity and ease of exploitation make it a high-priority target.
Refer to the praisonai security advisories on their official website or GitHub repository for the latest information and updates.
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