Critical Samba Flaw Lets Attackers Take Over Systems Without Logging In

Critical Samba vulnerability CVE-2026-4480 allows remote code execution on Unix systems. Patch now or remove %J from smb.conf for safety.

By Content Team

May 31, 2026

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A maximum-severity vulnerability in Samba's printing subsystem — CVE-2026-4480, CVSS 10.0 — lets unauthenticated attackers run arbitrary commands on affected Linux and Unix systems. The flaw lives in the %J substitution parameter used in print commands, which passes client-controlled input directly into a shell without escaping special characters. Since many Samba setups allow guest print job submissions by default, no credentials are needed to exploit it.

Patches are out: Samba versions 4.22.10, 4.23.8, and 4.24.3 fix the issue. Systems using printing = cups or iprint aren't affected. If patching isn't immediate, removing %J from your smb.conf print command is the safest workaround.

Source: Cybersecurity News

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