# CVE-2026-39891: PraisonAI has a Template Injection in Agent Tool Definitions

> Attackers can execute arbitrary code via template injection in PraisonAI agent tools when user input is not escaped.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 Apr 2026
- **Updated:** 9 Apr 2026
- **Also known as:** GHSA-hwg5-x759-7wjg, PYSEC-2026-2917

## What is CVE-2026-39891?

CVE-2026-39891 is a high-severity code injection vulnerability in MervinPraison PraisonAI, published on 8 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

PraisonAI is a multi-agent teams system. Prior to 4.5.115, 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, template expressions in the input are executed rather than treated as literal text. This vulnerability is fixed in 4.5.115.

Weakness: CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2026-39891?

3 open source packages ship an affected version, including praisonai. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `praisonai` | PyPI | All versions | 4.5.115 |
| `praisonai` | PyPI | All versions | 4.5.115 |
| `praisonai` | PyPI | All versions | 4.5.115 |

Products: Praison Praisonai.

## How do I fix CVE-2026-39891?

Upgrade praisonai to 4.5.115 or later.

## Is CVE-2026-39891 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39891 exists.

## Other vulnerabilities in MervinPraison PraisonAI

- [CVE-2026-39888](https://insights.sbomify.com/CVE-2026-39888/): PraisonAIAgents has a sandbox escape via exception frame traversal in `execute_code` (subprocess mode) (critical 10.0)
- [CVE-2026-41497](https://insights.sbomify.com/CVE-2026-41497/): Incomplete fix for CVE-2026-34935: Command Injection in MervinPraison/PraisonAI (critical 9.8)
- [CVE-2026-40288](https://insights.sbomify.com/CVE-2026-40288/): PraisonAI: Critical RCE via `type: job` workflow YAML (critical 9.8)
- [CVE-2026-39890](https://insights.sbomify.com/CVE-2026-39890/): PraisonAI Affected by Remote Code Execution via YAML Deserialization in Agent Definition Loading (critical 9.8)
- [CVE-2026-34934](https://insights.sbomify.com/CVE-2026-34934/): PraisonAI: Second-Order SQL Injection in `get_all_user_threads` (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-39891 and fix it if it is affected.

What it is: CVE-2026-39891 is a high-severity code injection vulnerability in MervinPraison PraisonAI, published on 8 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39891 exists.

Affected packages and fixed versions:
- praisonai (PyPI): affected all versions; fixed in 4.5.115
- praisonai (PyPI): affected all versions; fixed in 4.5.115
- praisonai (PyPI): affected all versions; fixed in 4.5.115

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-39891/ (Markdown: https://insights.sbomify.com/CVE-2026-39891/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39891
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39891
- OSV: https://osv.dev/vulnerability/CVE-2026-39891

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-39891/
Summaries are generated and may contain mistakes; the official description above is the record.