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Fencer Intel
medium 4.9

CVE-2026-63441 json

2FAuth: SSRF guard misses IPv6 NAT64 prefixes, allowing image fetch to reach internal/metadata targets

published 4mo ago modified 2d ago also EUVD-2026-118489 , GHSA-wc8m-7c5g-xrrc

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository Bubka/2FAuth. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
4.9
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 24%
public exploits
0
none known

Summary

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.

Patch / fix

  • 2fauth 2fauth 8.0.0

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2d ago

Exploit prediction

0.31% chance of exploitation in the next 30 days, higher than 24% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 4.9 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
CNA 4.0 4.9 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • Bubka 2FAuth

Classification

Weakness
  • CWE-918 Server-Side Request Forgery

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of Bubka/2FAuth published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.