Muteki CVE-2026-79623

Exploitation requires low-level privileges (PR:L per CVSS 4.0 vector) - the attacker must have some authenticated or credentialed access to the Muteki application, or the ability to influence the contents of the .claude/settings.json configuration file processed by the Default Local Worker Backend. The attack is network-reachable (AV:N) with low complexity (AC:L) and no required user interaction (UI:N), meaning once authentication is satisfied the exploit can be executed remotely without further prerequisites. No special non-default configuration is indicated as required beyond running the Muteki software itself. Limiting factors: requires at minimum low-privilege access to the application; the product's small and declining user base limits the attack surface globally; and the obscurity of the application reduces adversarial targeting interest compared to mainstream software.

The CVSS 4.0 score of 5.3 with low VC/VI/VA impacts is notably lower than what CWE-78 OS command injection typically warrants - a discrepancy that should prompt verification. Independent assessment suggests the actual integrity and confidentiality impacts could be higher if command execution is unrestricted on the server; the vendor's low impact scoring may reflect application-level sandboxing or a highly constrained execution environment, but this is not confirmed from available data. The E:P exploit maturity flag in the CVSS 4.0 vector confirms a public POC exists, which materially raises real-world exploitability. However, the product is obscure (single GitHub repository, small open-source project) and the maintainer has announced a shutdown, meaning the installed base is minimal. No EPSS data is available in the provided intelligence. KEV status is absent, so no confirmed active exploitation is on record. The realistic risk is narrow: low prevalence product with a public POC and no patch path - dangerous for the small number of deployments that exist, but not a broad enterprise threat.

An attacker with low-privilege access to the Muteki application - such as an authenticated API user or a user with write access to the application's configuration path - crafts a payload embedding OS command metacharacters into an input field or configuration value processed by the Default Local Worker Backend. The application passes this unsanitized input to a system shell call, executing the injected commands with the privileges of the Muteki process. A public POC exists at https://github.com/micr0softDrestlife/muteki_vul_report, lowering the barrier to exploitation significantly.