# CVE-2026-78009: Fireware OS Out-of-Bounds Read in iked Allows Unauthenticated Denial of Service (DoS)

> Remote unauthenticated attackers can cause a denial of service in VPN processing by sending crafted traffic to WatchGuard Fireware OS.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Aug 2026
- **Updated:** 3 Sep 2026
- **Also known as:** GHSA-j294-c4gm-rwh3

## What is CVE-2026-78009?

CVE-2026-78009 is a high-severity denial of service vulnerability in WatchGuard Fireware OS, published on 27 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An out-of-bounds read vulnerability in the WatchGuard Fireware OS iked process allows a remote unauthenticated attacker to create a Denial of Service (DoS) condition in VPN processing by sending specially crafted network traffic.

Weakness: CWE-20 (Improper Input Validation), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-78009?


## How do I fix CVE-2026-78009?

No fix has been published for CVE-2026-78009 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-78009 being exploited?

There is no known exploitation of CVE-2026-78009 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-78009 and fix it if it is affected.

What it is: CVE-2026-78009 is a high-severity denial of service vulnerability in WatchGuard Fireware OS, published on 27 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-78009 in the wild and no public exploit code.

Affected product: WatchGuard Fireware OS. 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-2026-78009/ (Markdown: https://insights.sbomify.com/CVE-2026-78009/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-78009
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-78009
- OSV: https://osv.dev/vulnerability/CVE-2026-78009

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-78009/
Summaries are generated and may contain mistakes; the official description above is the record.