NN-2026:21-01
Update bundle signature bypass in Guardian/CMC before 26.4.0
| Advisory ID | NN-2026:21-01 |
|---|---|
| Topic | Update bundle signature bypass in Guardian/CMC before 26.4.0 |
| CWE Impact | CWE-347: Improper Verification of Cryptographic Signature |
| Issue date | 2026-10-29 |
| Affects | Guardian, CMC < v26.4.0 |
| CVE Name(s) | CVE-2026-33923 |
| CVSS Details | CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H |
| CVSS Score | 7.5 (CVSS v4.0) 7.2 (CVSS v3.1) |
| CVE Risk Level | High (CVSS v4.0) High (CVSS v3.1) |
| Risk Level for Nozomi customers | High |
Summary
A signature verification vulnerability was discovered in the update installation functionality due to inconsistent validation of the update bundle contents.
Impact
An attacker with administrative privileges can remotely supply a crafted update bundle that passes signature verification but runs an unsigned script when the bundle is installed. The script runs with root privileges, allowing the attacker to read or modify sensitive data, change the appliance configuration, or shut down the appliance.
Affected Products
Guardian, CMC < v26.4.0
Workarounds and Mitigations
Use internal firewall features to limit access to the web management interface. Review all accounts with administrative privileges and delete unnecessary ones. Install update bundles only when they come from trusted Nozomi Networks sources.
Solutions
Upgrade to v26.4.0 or later.
Modification History
Related Links
Acknowledgements
We thank the following parties for their efforts:
- Andrea Palanca of Nozomi Networks Product Security team for finding this issue during an internal investigation
Contact
Nozomi Networks Product Security team can be reached at prodsec@nozominetworks.com.More contact details on the PSIRT page.