CVE-2026-55245 Bifrost: SSRF deny-list incomplete: isPublicIP permits CGNAT, IPv6 6to4/NAT64, and site-local in FetchAndEncodeURL
Remote attackers can exploit incomplete IP filtering to access internal services and cloud metadata via crafted URLs in the Bifrost AI gateway.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-55245?
CVE-2026-55245 is a high-severity server-side request forgery vulnerability in maximhq bifrost, published on 28 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-918
Which versions are affected by CVE-2026-55245?
3 open source packages ship an affected version, including github.com/maximhq/bifrost/core.
| Package | Affected | Fixed in |
|---|---|---|
github.com/maximhq/bifrost/core Go | All versions | 1.5.17 |
github.com/maximhq/bifrost/core Go | All versions | 1.5.17 |
github.com/maximhq/bifrost/core Go | All versions | 1.5.17 |
How do I fix CVE-2026-55245?
Upgrade github.com/maximhq/bifrost/core to 1.5.17 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-55245 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55245 exists.
Sources
Also known as GHSA-w98g-5w9p-p3rc, GO-2026-6320, MINI-78xv-jqw9-mrfv, MINI-8xj3-g575-v8m3.