Tool Call Limit Bypass in Pydantic AI Harness by Pydantic
CVE-2026-114386

6.3MEDIUM

Key Information:

Vendor

Pydantic

Status
Pydantic-ai-harness
Vendor
CVE Published:
21 October 2026

What is CVE-2026-114386?

The Pydantic AI Harness prior to version 0.59.0 is susceptible to a tool call limit bypass vulnerability in its CodeMode toolset. This flaw allows users or malicious content to execute nested tool calls via the run_code function without proper enforcement of usage limits. As a result, operations can exceed established limits on resource-intensive tools, potentially leading to unexpected costs or side effects. Prompt action is recommended to secure applications by updating to the latest version and mitigate risks.

Affected Version(s)

pydantic-ai-harness 0 < 0.59.0

References

https://github.com/pydantic/pydantic-ai/pull/10362
issue-trackingpatch
https://github.com/pydantic/pydantic-ai/commit/eb27b2b89f...
patch
https://github.com/pydantic/pydantic-ai/releases/tag/v2.59.0
release-notes

CVSS V4

Score:
6.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
Low
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

CBF
.