Is CVE-2026-90811 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-90811 being exploited in the wild.

How severe is CVE-2026-90811?

Low severity, with a CVSS score of 3.3, published 14 September 2026.

Which products and versions are affected?

Cosmicstack Labs Mercury Agent up to 1.2.0.

Is there a fix for CVE-2026-90811?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-90811 attacked?

It is attacked with local access.

Am I affected by CVE-2026-90811?

Check whether you run Cosmicstack Labs Mercury Agent at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-90811: Cosmicstack Labs Mercury Agent shell permission bypass via wc

CVE-2026-90811 · Severity: low · CVSS 3.3 · Published 2026-09-14

Mercury Agent is an AI agent framework with permission controls for shell command execution. A flaw in the shell permission manifest allows attackers to bypass the approval system and disclose metadata for files outside the approved working directory by using the `wc --files0-from` flag with a crafted file list, even though the command itself appears to be a safe read-only operation.

Technologies: Cosmicstack Labs Mercury Agent. Vendors: Cosmicstack Labs.

Quick answers

Is CVE-2026-90811 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-90811 being exploited in the wild.
How severe is CVE-2026-90811?: Low severity, with a CVSS score of 3.3, published 14 September 2026.
Which products and versions are affected?: Cosmicstack Labs Mercury Agent up to 1.2.0.
Is there a fix for CVE-2026-90811?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-90811 attacked?: It is attacked with local access.
Am I affected by CVE-2026-90811?: Check whether you run Cosmicstack Labs Mercury Agent at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability is a policy mismatch in the PermissionManager.checkShellCommand function in mercury-agent/src/capabilities/permissions.ts. The shell permission manifest auto-approves `wc *` as a safe read-only command, but the path containment check only scans literal path tokens in the command string and fails to inspect paths that will be dereferenced later at execution time. An attacker can craft a command like `wc --files0-from=list0.bin` where `list0.bin` contains NUL-separated absolute paths to out-of-scope files. The command bypasses approval and executes through execSync, leaking file metadata via the command output. This requires local execution and the ability to create or control a file within the current workspace. The vulnerability has been disclosed publicly with a proof-of-concept but the vendor has not responded.

Affected products

Cosmicstack Labs Mercury Agent up to 1.2.0

Timeline

2026-09-14: disclosed
other: Public exploit available; vendor issue report filed but no response yet

References

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