CVE-2026-0400 Denial of service in SonicOS

What is CVE-2026-0400?

CVE-2026-0400 is a medium-severity denial of service vulnerability in Sonicwall Sonicos, published on 24 Feb 2026. An attacker needs administrator access to exploit it, with no action from the victim.

Official description

A post-authentication Format String vulnerability in SonicOS allows a remote attacker to crash a firewall.

Weakness: CWE-134

Which versions are affected by CVE-2026-0400?

It affects 1 product.

Products include Sonicwall Sonicos.

How do I fix CVE-2026-0400?

No fix has been published for CVE-2026-0400 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-0400 being exploited?

There is no known exploitation of CVE-2026-0400 in the wild and no public exploit code.

Other vulnerabilities in Sonicwall Sonicos

• CVE-2020-5135 SonicWall SonicOS Buffer Overflow Exploited Critical 9.8
• CVE-2024-40766 SonicWall SonicOS Improper Access Control Exploited Critical 9.3
• CVE-2024-53704 SonicWall SonicOS SSLVPN Improper Authentication Exploited High 8.2
• CVE-2025-40600 Denial of service in SonicOS Critical 9.8
• CVE-2024-22394 Auth bypass in SonicOS Critical 9.8

All Sonicwall Sonicos vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-3q93-28v9-5x6v.