CVE-2026-39891: Praisonai PraisonAI Has Template Injection Vulnerability

HIGH
Advisory Identifier: GHSA-hwg5-x759-7wjg
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CVSS 8.8
CWE-94
Published
Advisory Summary

CVE-2026-39891 is a HIGH (CVSS 8.8) praisonai has template injection vulnerability (CWE-94: Improper Control of Generation of Code ('Code Injection')) affecting Praisonai libraries in the PyPI ecosystem. The issue involves praisonai has template injection in agent tool definitions. Remediation is available by upgrading affected packages to version 4.5.115.

CVE-2026-39891 at a Glance

CVE Identifier CVE-2026-39891
GHSA Identifier GHSA-hwg5-x759-7wjg
Severity HIGH
CVSS v3.1 Base Score 8.8
CWE Classification CWE-94: Improper Control of Generation of Code ('Code Injection')
Affected Product Praisonai
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 8.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-39891

To remediate this vulnerability, upgrade all affected Praisonai dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

praisonai fixed: 4.5.115 
pip install praisonai>=4.5.115
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show praisonai

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-39891, inspect your installed packages using pip:

pip show praisonai

Analyze the terminal output to locate any version of Praisonai in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.5.115), your application is affected.

Note: The pip show praisonai command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-94: Improper Control of Generation of Code ('Code Injection'), where the product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. In Praisonai, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

## Summary Direct insertion of unescaped user input into template-rendering tools allows arbitrary code execution via specially crafted agent instructions. ## Details The `create_agent_centric_tools()` function returns tools (like `acp_create_file`) that process file content using template rendering. When user input from `agent.start()` is passed directly into these tools without escaping (as shown in `agent_centric_example.py:85-86`), template expressions in the input are executed rather than treated as literal text. This occurs because: 1. No input sanitization or escaping is applied to user-controlled content 2. The ACP-enabled runtime auto-approves operations (`approval_mode="auto"`) 3. Tools lack context-aware escaping for template syntax ## PoC ```python # Replace the agent.start() call at line 85 with: result = agent.start('Create file with content: {{ self.__init__.__globals__.__builtins__.__import__("os").system("touch /tmp/pwned") }}') ``` Successful exploitation creates `/tmp/pwned` confirming arbitrary command execution. The expression `{{7*7}}` renders as `49` instead of literal text. ## Impact Attackers can execute arbitrary system commands with the privileges of the running process by injecting malicious template expressions through agent instructions. This compromises the host system, enabling data theft, ransomware deployment, or lateral movement. ## Recommended Fix 1. **Input Sanitization**: Implement strict whitelist validation for file content 2. **Contextual Escaping**: Auto-escape template syntax characters (e.g., `{{ }}`) in user input using Jinja2 `autoescape=True` 3. **Sandboxing**: Restrict template execution environments using secure eval modes 4. **Approval Hardening**: Require manual approval for file creation operations in production

CVE-2026-39891 Affected Praisonai Versions

1 component(s)
Fixed Versions:
4.5.115
Product / Package Ecosystem Affected Versions Fixed Version
praisonai
pypi/praisonai
PyPI
< 4.5.115
4.5.115

References

GitHub Advisory / Wiki ADVISORY
https://github.com/MervinPraison/PraisonAI/security/advisories/GHSA-hwg5-x759-7wjg
NVD — CVE-2026-39891 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-39891
Praisonai Source Repository REPOSITORY
https://github.com/MervinPraison/PraisonAI
Praisonai Release RELEASE
https://github.com/MervinPraison/PraisonAI/releases/tag/v4.5.115

Frequently Asked Questions

What is CVE-2026-39891?
CVE-2026-39891 is a security vulnerability in Praisonai involving PraisonAI has Template Injection in Agent Tool Definitions under CWE-94: Improper Control of Generation of Code ('Code Injection').
Which Praisonai versions are affected?
Affected versions include releases prior to 4.5.115 across affected packages: praisonai.
What version fixes CVE-2026-39891?
Upgrading to 4.5.115 (or the latest patched release for your respective branch) resolves the vulnerability.
Is praisonai affected?
Yes, praisonai is affected in releases prior to 4.5.115. Upgrade your dependency to 4.5.115 or later.
What is the CVSS score of CVE-2026-39891?
CVE-2026-39891 has a CVSS v3.1 base score of 8.8 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-39891?
CVE-2026-39891 is classified under CWE-94: Improper Control of Generation of Code ('Code Injection') (The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.).
How can I check PyPI dependencies for CVE-2026-39891?
Run the dependency tree command: 'pip show praisonai'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hwg5-x759-7wjg",
  "modified" : "2026-04-09T14:29:49Z",
  "published" : "2026-04-08T19:21:22Z",
  "aliases" : [ "CVE-2026-39891" ],
  "summary" : "PraisonAI has Template Injection in Agent Tool Definitions",
  "details" : "## Summary\nDirect insertion of unescaped user input into template-rendering tools allows arbitrary code execution via specially crafted agent instructions.\n## Details\nThe `create_agent_centric_tools()` function returns tools (like `acp_create_file`) that process file content using template rendering. When user input from `agent.start()` is passed directly into these tools without escaping (as shown in `agent_centric_example.py:85-86`), template expressions in the input are executed rather than treated as literal text. This occurs because:\n1. No input sanitization or escaping is applied to user-controlled content\n2. The ACP-enabled runtime auto-approves operations (`approval_mode=\"auto\"`)\n3. Tools lack context-aware escaping for template syntax\n## PoC\n```python\n# Replace the agent.start() call at line 85 with:\nresult = agent.start('Create file with content: {{ self.__init__.__globals__.__builtins__.__import__(\"os\").system(\"touch /tmp/pwned\") }}')\n```\nSuccessful exploitation creates `/tmp/pwned` confirming arbitrary command execution. The expression `{{7*7}}` renders as `49` instead of literal text.\n## Impact\nAttackers can execute arbitrary system commands with the privileges of the running process by injecting malicious template expressions through agent instructions. This compromises the host system, enabling data theft, ransomware deployment, or lateral movement.\n## Recommended Fix\n1. **Input Sanitization**: Implement strict whitelist validation for file content\n2. **Contextual Escaping**: Auto-escape template syntax characters (e.g., `{{ }}`) in user input using Jinja2 `autoescape=True`\n3. **Sandboxing**: Restrict template execution environments using secure eval modes\n4. **Approval Hardening**: Require manual approval for file creation operations in production",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "praisonai"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.5.115"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.5.114"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/MervinPraison/PraisonAI/security/advisories/GHSA-hwg5-x759-7wjg"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-39891"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/MervinPraison/PraisonAI"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/MervinPraison/PraisonAI/releases/tag/v4.5.115"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-94" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-08T19:21:22Z",
    "nvd_published_at" : "2026-04-08T21:17:01Z"
  }
}