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CVE-2026-55245

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

HIGH
8.7
CVSS Score
Published: August 28, 2026 at 06:24 PM UTC
Updated: September 9, 2026 at 09:27 PM UTC
1 product affected across 1 vendorBifrost

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Severity
HIGH8.7
Exploit prediction
EPSS 0.6%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Bifrost· Maximhq
60%
v < 1.5.17
Affected range stops below 1.5.17, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (4)

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

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.7HIGHGitHub_M
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-918

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