RCE in Mervinpraison Praisonai
CVE-2026-40158
PraisonAI is a multi-agent teams system. Prior to 4.5.128, PraisonAI's AST-based Python sandbox can be bypassed using type.__getattribute__ trampoline, allowing arbitrary code execution when running untrusted agent code. The _execute_code_direct function in praisonaiagents/tools/python_tools.py uses AST filtering to block dangerous Python attributes like __subclasses__, __globals__, and __bases__. However, the filter only checks ast.Attribute nodes, allowing a bypass. The sandbox relies on AST-based filtering of attribute access but fails to account for dynamic attribute resolution via built-in methods such as type.getattribute, resulting in incomplete enforcement of security restrictions. The string '__subclasses__' is an ast.Constant, not an ast.Attribute, so it is never checked against the blocked list. This vulnerability is fixed in 4.5.128.
Vulnerability class: RCE (Remote Code Execution)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.6 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.002 (11.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 12th percentile — 11.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: -0.000
Affected products
- Mervinpraison Praisonai — versions < 4.5.128
- Praison Praisonai
Weakness classification (CWE)
References
- github.com/MervinPraison/PraisonAI/security/advisories/GHSA-3c4r-6p77-xwr7 (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-40158?
- CVE-2026-40158 is a high-severity vulnerability in Mervinpraison Praisonai, classified under Code Injection. CVSS score: 8.6/10. Published 2026-04-10.
- How severe is CVE-2026-40158?
- High severity. CVSS v3 base score is 8.6 out of 10.