# CVE-2026-66154: Security feature bypass in GMS

> Insufficient certificate validation in SonicWall GMS allows attackers to perform unauthorized changes via Man-in-the-Middle attacks.

- **Severity:** High 8.3 (`CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 11 Aug 2026
- **Updated:** 12 Aug 2026
- **Also known as:** GHSA-5h7r-wrwv-5rj5

## What is CVE-2026-66154?

CVE-2026-66154 is a high-severity vulnerability in SonicWall GMS, published on 11 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An insufficient certificate validation in a privileged communication workflow, was identified in a GMS application 9.5.1 (Build 9510.1044) and earlier versions which, under a successful MitM attack and controlled network conditions, could permit unauthorized changes.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2026-66154?


## How do I fix CVE-2026-66154?

No fix has been published for CVE-2026-66154 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-66154 being exploited?

There is no known exploitation of CVE-2026-66154 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-66154 and fix it if it is affected.

What it is: CVE-2026-66154 is a high-severity vulnerability in SonicWall GMS, published on 11 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-66154 in the wild and no public exploit code.

Affected product: SonicWall GMS. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-66154/ (Markdown: https://insights.sbomify.com/CVE-2026-66154/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-66154
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-66154
- OSV: https://osv.dev/vulnerability/CVE-2026-66154

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-66154/
Summaries are generated and may contain mistakes; the official description above is the record.