GNU Guix Vulnerabilities Let Attackers Overwrite Arbitrary Files and Escalate Privileges

A security researcher disclosed multiple serious vulnerabilities in GNU Guix's substitute handling that allow attacker-controlled substitutes or network impersonation to write arbitrary files as the guix-daemon user (potentially affecting root-owned locations like /etc/passwd), return mismatched metadata to force package substitution, and expose sensitive data via file:// URIs and malformed narinfo responses; fixes were released and administrators are advised to upgrade to a specified commit or disable substitutes and restart the guix-daemon as interim mitigation.