How to Fix CVE-2026-0400: SonicOS (Bundle Sibling)
By Sai Kiran Pandrala. Last verified: 2026-05-25.
CVE-2026-0400 is a sibling vulnerability in the same vendor advisory as CVE-2026-0399. Apply the same patched build and you close both. The technical detail below is what differs.
| Severity | 4.9 (Medium) |
|---|---|
| Actively exploited? | No public listing in CISA KEV |
| Affected | SonicOS 7.0.1-5169 and older versions; SonicOS 7.3.1-7013 and older versions; SonicOS 8.1.0-8017 and older versions |
| Fixed in | Same patched build as CVE-2026-0399 |
| Type (CWE) | CWE-134 Use of Externally-Controlled Format String |
What's different about CVE-2026-0400?
A post-authentication Format String vulnerability in SonicOS allows a remote attacker to crash a firewall.
How to fix CVE-2026-0400
Apply the patched build per the primary write-up: How to Fix CVE-2026-0399. All commands, verification steps, and rollback notes for SonicOS are listed there.
Frequently asked questions
Does the CVE-2026-0399 patch close CVE-2026-0400?
Yes. Both CVEs are addressed by the same vendor patch. Applying the patched build closes the full bundle.
Is CVE-2026-0400 listed in CISA KEV?
No public KEV listing at the time of this writing.
Where is the official advisory?
See https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2026-0001
References
- Official vendor advisory: https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2026-0001
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-0400
- CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
- Primary: How to Fix CVE-2026-0399
*Written by Sai Kiran Pandrala. Part of the SonicOS bundle. Full procedure at how-to-fix-cve-2026-0399.*