Junglewise Threat Intelligence

CVE-2026-34939: MervinPraison PraisonAI ReDoS in MCPToolIndex.search_tools

CVE-2026-34939 · Severity: medium · CVSS 6.5 · Published 2026-04-03

Technologies: praisonai (PyPI), Praisonai. Vendors: PyPI, Praison, MervinPraison.

Executive brief

PraisonAI is a system used to manage and coordinate teams of AI agents. A security flaw allows an attacker to send a specially crafted search query that freezes the application's processing engine. This results in a complete service outage, preventing the AI agents from performing their tasks and disrupting operations.

Technical details

A Regular Expression Denial of Service (ReDoS) vulnerability exists in the MCPToolIndex.search_tools() function of PraisonAI. The root cause is the direct compilation of user-provided strings into Python regular expressions using the 're' module without validation or execution timeouts. An attacker can provide a regex pattern designed to trigger catastrophic backtracking, such as '(a+)+ , which exhausts CPU resources and blocks the Python thread for extended periods. This vulnerability is reachable over the network; while the CVSS indicates low privileges are required, the advisory notes that the MCP server HTTP transport often runs without an API key by default. The issue is resolved in version 4.5.90.

Affected products

  • MervinPraison PraisonAI < 4.5.90

Timeline

  • 2026-03-31: advisory: Vendor advisory published on GitHub
  • 2026-04-03: disclosed: CVE published to NVD
  • 2026-04-03: patched: Fix released in version 4.5.90

References

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