# CVE-2026-55473: Server-side request forgery in homebox

> Authenticated users can bypass SSRF protections via NAT64 prefixes to access cloud metadata or internal hosts, disclosing sensitive credentials.

- **Severity:** Medium 6.0 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 Sep 2026
- **Updated:** 29 Sep 2026
- **Also known as:** GHSA-r9pf-rg22-655m

## What is CVE-2026-55473?

CVE-2026-55473 is a medium-severity server-side request forgery vulnerability in sysadminsmedia homebox, published on 21 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

HomeBox is a home inventory and organization system. Prior to 0.26.0, the default-on BlockBogonNets and BlockCloudMetadata notifier SSRF protections in backend/internal/sys/validate/notifier_url.go do not inspect IPv4 destinations embedded in the NAT64 prefixes 64:ff9b::/96 and 64:ff9b:1::/48. An authenticated user can submit a generic:// notifier through POST /v1/notifiers or POST /v1/notifiers/test, and on a Homebox instance that egresses through NAT64/DNS64, the gateway can translate an accepted IPv6 destination to cloud metadata, localhost, or another internal IPv4 host. The notifier test path returns delivery result information, and Shoutrrr propagates the response, providing feedback that can disclose retrieved metadata such as temporary credentials. Without NAT64 egress, the crafted IPv6 destination is not routable, but the guard still incorrectly classifies it as safe. This issue is fixed in version 0.26.0.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-55473?


## How do I fix CVE-2026-55473?

No fix has been published for CVE-2026-55473 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-55473 being exploited?

There is no known exploitation of CVE-2026-55473 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55473 and fix it if it is affected.

What it is: CVE-2026-55473 is a medium-severity server-side request forgery vulnerability in sysadminsmedia homebox, published on 21 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-55473 in the wild and no public exploit code.

Affected product: sysadminsmedia homebox. 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-2026-55473/ (Markdown: https://insights.sbomify.com/CVE-2026-55473/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55473
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55473
- OSV: https://osv.dev/vulnerability/CVE-2026-55473

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55473/
Summaries are generated and may contain mistakes; the official description above is the record.