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TI-2026-39919 Aliases CVE-2026-55245GHSA-w98g-5w9p-p3rc

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

Priority HIGH 77CWE-918Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
None · High · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00611 49th percentileScored 2026-11-07
Fix Fixed bifrost (maximhq): 1.5.17github.com/maximhq/bifrost/core (Go): 1.5.17

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
maximhqbifrostbefore 1.5.171.5.17Patch availableCNA
—github.com/maximhq/bifrost/core (Go)before 1.5.171.5.17Patch availableGHSA-w98g-5w9p-p3rc
  • bifrost Vendormaximhq Affected before 1.5.17 Fixed in 1.5.17 Patch available CNA
  • github.com/maximhq/bifrost/core (Go) Vendor— Affected before 1.5.17 Fixed in 1.5.17 Patch available GHSA-w98g-5w9p-p3rc

Remediation

  • Fix · CNA bifrost (maximhq) Fixed in 1.5.17
  • Fix · GHSA-w98g-5w9p-p3rc github.com/maximhq/bifrost/core (Go) Fixed in 1.5.17 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55245
  2. 2026-10-03 Alias added: GHSA-w98g-5w9p-p3rc

References

Other 5

  • TI-2026-61769 Bifrost unauthenticated remote code execution via MCP stdio client registration CVSS 3.1CRITICAL 9.8
  • TI-2026-59029 Unauthenticated RCE via Custom Plugin HTTP Path on Dynamically Linked Builds CVSS 3.1HIGH 8.1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences