# 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.

- **Severity:** High 8.7 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** GHSA-w98g-5w9p-p3rc, GO-2026-6320, MINI-78xv-jqw9-mrfv, MINI-8xj3-g575-v8m3

## 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 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-55245?

3 open source packages ship an affected version, including github.com/maximhq/bifrost/core.


| Package | Ecosystem | 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.

## Is CVE-2026-55245 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55245 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55245 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55245 exists.

Affected packages and fixed versions:
- github.com/maximhq/bifrost/core (Go): affected all versions; fixed in 1.5.17
- github.com/maximhq/bifrost/core (Go): affected all versions; fixed in 1.5.17
- github.com/maximhq/bifrost/core (Go): affected all versions; fixed in 1.5.17

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-55245/ (Markdown: https://insights.sbomify.com/CVE-2026-55245/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55245
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55245
- OSV: https://osv.dev/vulnerability/CVE-2026-55245

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55245/
Summaries are generated and may contain mistakes; the official description above is the record.