Vulnerability · Published Aug 28, 2026 · Assigned by GitHub_M
CVE-2026-55245Bifrost: SSRF deny-list incomplete: isPublicIP permits CGNAT, IPv6 6to4/NAT64, and site-local in FetchAndEncodeURL
High 8.7
In plain English
A high-severity server-side request forgery in bifrost from maximhq. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Bifrost is an enterprise AI gateway for routing requests to model providers. Prior to 1.5.17, the isPublicIP function in core/providers/utils/fetch.go, reached through FetchAndEncodeURL for Bedrock and Vertex image or document URLs, classifies Carrier-Grade NAT 100.64.0.0/10, IPv6 6to4 2002::/16, NAT64 64:ff9b::/96 and 64:ff9b:1::/48, and deprecated IPv6 site-local fec0::/10 addresses as public. A remote attacker who controls a multimodal request URL can make the gateway fetch internal services, including a cloud instance metadata endpoint encoded through 6to4 or NAT64. This issue is fixed in version 1.5.17.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/maximhq/bifrost/core | 1.5.17 | GHSA-w98g-5w9p-p3rc |
| Go | github.com/maximhq/bifrost/core | 1.5.17 | GO-2026-6320 |
Affected products (as reported)
Weakness: CWE-918 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
References
- https://github.com/maximhq/bifrost/security/advisories/GHSA-w98g-5w9p-p3rc x_refsource_CONFIRM
- https://github.com/maximhq/bifrost/pull/4092 x_refsource_MISC
- https://github.com/maximhq/bifrost/commit/54ec431fc5255ff42c36420d88549477e0b33d89 x_refsource_MISC
- https://github.com/maximhq/bifrost/releases/tag/core/v1.5.17 x_refsource_MISC