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.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
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
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.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-55473 being exploited?
There is no known exploitation of CVE-2026-55473 in the wild and no public exploit code.
Sources
Also known as GHSA-r9pf-rg22-655m.