Vulnerability · Published Sep 15, 2026 · Assigned by VulnCheck

CVE-2026-91987atomic-agents-stack before 1.1.0 Cost Guardrail Bypass via Unknown Model

Medium 6.5

In plain English

A medium-severity resource allocation without limits in atomic-agents-stack from dep0we. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium

Exploit odds (30 days)0.5%top 58.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

atomic-agents-stack before 1.1.0 contains a cost-guardrail bypass in the _estimate_batch_cost function that returns zero cost for unknown models not in the pricing table. Attackers can configure deployments with unknown model identifiers to bypass daily cost caps and exceed budget limits in parallel batch operations.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
PyPI	atomic-agents-stack	1.1.0	GHSA-j659-8xh6-5pq5

Affected products (as reported)

Vendor	Product	Versions
dep0we	atomic-agents-stack	0 – before 1.1.0

Weakness: CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

References

GitHub Security Advisory (GHSA-j659-8xh6-5pq5) vendor-advisory
VulnCheck Advisory: atomic-agents-stack before 1.1.0 Cost Guardrail Bypass via Unknown Model third-party-advisory