Coding-agent CLI honours managed configuration from a world-writable shared path

coding-agent-shared-config-trust is a high severity check in the ai category, written in shell. Its source is templates/ai/coding-agent/coding-agent-shared-config-trust.sh in cert-x-gen-templates.

What it checks

Plants an identical benign managed-settings file in two shared config roots that differ only in permissions - one 0700, one world-writable 0777 - and runs the coding-agent CLI against each. Honouring the 0700 copy establishes that the tool reads system-wide settings at all; honouring the 0777 copy as well proves it applies configuration from a directory any local user can write to, with no ownership, permission or approval gate. That is local privilege escalation into the agent (CVE-2026-35603 class).

There is a playbook for this check

Execution authority: what a coding-agent CLI will run on someone else’s say-so sets out the use case, the probe flow, the oracle, and the fixture that proves it in both directions.

Header

Field	Value
Id	coding-agent-shared-config-trust
Severity	high
Language	shell
Category	ai
Author	CERT-X-GEN Security Team
Template version	not recorded
Confidence	95
CVSS	not recorded
Weakness	CWE-732
Tags	ai, coding-agent, cli, config-trust, privilege-escalation, hooks, cwe-732, cwe-276, cwe-15, cve-2026-35603
Target kind	cli
Oracle	property

Conventions of the repository, not fields the engine reads

@target_kinds and @oracles are documented in the templates repository’s contribution guide, and cxg’s annotation parser does not carry them into a template’s metadata. Nothing at scan time selects on them. The annotation header schema is every field the parser does read.

References

Declared in the header. cxg parses @references and then discards it, and nothing at scan time reads it, so this is the only place the links a template cites are surfaced.

• https://cymulate.com/blog/cve-2026-35603-ai-coding-tools-privilege-escalation/

Run it

To see what the copy on your machine says about itself, and to confirm it is installed at all:

cxg template info coding-agent-shared-config-trust

The id it prints is the one to pass anywhere a template is selected. See cxg template for the rest of the subcommand, Scan a target for running a scan, and A match is not a finding for how to read what comes back.

Related

• Template catalog is the whole corpus.
• ai is the rest of this category.
• Templates by weakness class groups checks by the defect they look for.
• Contribute a template is the route from a check you needed and could not find to a merged one.