What’s Vulnerable › Vulnerabilities

CVE-2026-55245: Bifrost: SSRF deny-list incomplete: isPublicIP permits CGNAT, IPv6 6to4/NAT64, and site-local in FetchAndEncodeURL

• Severity: high (CVSS 8.7 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-28 · updated 2026-09-09
• Weakness: CWE-918

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 products

• maximhq Bifrost: before 1.5.17

References

• https://github.com/maximhq/bifrost/commit/54ec431fc5255ff42c36420d88549477e0b33d89
• https://github.com/maximhq/bifrost/pull/4092
• https://github.com/maximhq/bifrost/releases/tag/core/v1.5.17
• https://github.com/maximhq/bifrost/security/advisories/GHSA-w98g-5w9p-p3rc
• https://github.com/maximhq/bifrost/security/advisories/GHSA-w98g-5w9p-p3rc

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