Vulnerability · Published Apr 3, 2026 · Assigned by GitHub_M

CVE-2026-34939PraisonAI: ReDoS via Unvalidated User-Controlled Regex in MCPToolIndex.search_tools()

Medium 6.5

In plain English

A medium-severity regular-expression denial of service in PraisonAI from MervinPraison. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 36% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium

Exploit odds (30 days)0.4%top 63.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

PraisonAI is a multi-agent teams system. Prior to version 4.5.90, MCPToolIndex.search_tools() compiles a caller-supplied string directly as a Python regular expression with no validation, sanitization, or timeout. A crafted regex causes catastrophic backtracking in the re engine, blocking the Python thread for hundreds of seconds and causing a complete service outage. This issue has been patched in version 4.5.90.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
PyPI	praisonai	4.5.90	GHSA-8w9j-hc3g-3g7f
PyPI	praisonai	4.5.90	PYSEC-2026-2907

Affected products (as reported)

Vendor	Product	Versions
MervinPraison	PraisonAI	< 4.5.90

Weakness: CWE-1333 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

References

https://github.com/MervinPraison/PraisonAI/security/advisories/GHSA-8w9j-hc3g-3g7f x_refsource_CONFIRM