Medium 6.0Published Sep 21, 2026

CVE-2026-55473HomeBox: Notifier SSRF guard misses NAT64 prefixes (64:ff9b::/96, 64:ff9b:1::/48) — generic:// URL reaches cloud metadata on NAT64 egress

Updated under an hour ago (2026-10-19 09:50 UTC)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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.

CVSS: 6.0 MEDIUM (v4.0, CNA)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
Weakness (CWE): CWE-918
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Sep 29, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

sysadminsmedia homebox sysadminsmedia:homebox (from the name)	before 0.26.0	CNA record

References

https://github.com/sysadminsmedia/homebox/security/advisories/GHSA-r9pf-rg22-655mx-refsource-confirm
https://github.com/sysadminsmedia/homebox/commit/42c52f7f7566b7fbd8017352187af20f552a4471x-refsource-misc
https://github.com/sysadminsmedia/homebox/releases/tag/v0.26.0x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.