What does upgrading Samba 4.18.11 to 4.21.0 fix?

Upgrading Samba from 4.18.11 to 4.21.0 clears 3 known vulnerabilities (1 critical, 1 high). 2 known issues remain in 4.21.0.

← Samba

Samba: 4.18.11 → 4.21.0

Samba · upgrade impact

From4.18.114 known issues To4.21.02 known issues

Upgrade impact: Minor upgrade. Minor releases are usually backwards-compatible, but can add or change behaviour — test in staging before production.

Fixed by upgrading to 4.21.0 iVulnerabilities that affect 4.18.11 but no longer affect 4.21.0 — the security gain from this upgrade, by exploited status then exploitation probability.

Exploited first, then by exploitation probability (EPSS).

CVE-2026-4408 CRITICAL EPSS 3% ✓ cleared in 4.21.0 CVE-2023-5568 MEDIUM EPSS 2% ✓ cleared in 4.21.0 CVE-2026-3012 HIGH EPSS 0% ✓ cleared in 4.21.0

Still open in 4.21.0 iKnown vulnerabilities that affect 4.21.0 too — upgrading to it does not clear these.

These affect 4.21.0 as well — a later release may be needed.

CVE-2026-2340 MEDIUM EPSS 1% → see advisory CVE-2025-0620 MEDIUM EPSS 1% → fixed in 4.22.2