2FAuth is a web app to manage Two-Factor Authentication (2FA) accounts and generate their security codes. Prior to 8.0.0, the otpauth image-fetch path validates a hostname through ValidatesUrls::isExternalHost() and then lets IconService::storeRemoteImage() resolve the same hostname again for the HTTP request. When external otpauth image fetching is enabled, an authenticated user controlling low-TTL authoritative DNS can return a public address during validation and an internal address during the later connection, bypassing the private-address deny list to reach loopback, private-network, link-local, or cloud metadata endpoints. This issue is fixed in version 8.0.0.
History

Fri, 06 Nov 2026 22:00:00 +0000

Type Values Removed Values Added
First Time appeared Bubka
Bubka 2fauth
Vendors & Products Bubka
Bubka 2fauth

Fri, 06 Nov 2026 20:30:00 +0000

Type Values Removed Values Added
Description 2FAuth is a web app to manage Two-Factor Authentication (2FA) accounts and generate their security codes. Prior to 8.0.0, the otpauth image-fetch path validates a hostname through ValidatesUrls::isExternalHost() and then lets IconService::storeRemoteImage() resolve the same hostname again for the HTTP request. When external otpauth image fetching is enabled, an authenticated user controlling low-TTL authoritative DNS can return a public address during validation and an internal address during the later connection, bypassing the private-address deny list to reach loopback, private-network, link-local, or cloud metadata endpoints. This issue is fixed in version 8.0.0.
Title 2FAuth: Authenticated SSRF via DNS rebinding in the otpauth image= icon fetch (validate-then-fetch TOCTOU)
Weaknesses CWE-367
CWE-918
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-11-06T20:18:43.907Z

Updated: 2026-11-06T20:18:43.907Z

Reserved: 2026-07-16T19:35:57.767Z

Link: CVE-2026-63440

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-11-06T21:17:10.137

Modified: 2026-11-06T21:17:10.137

Link: CVE-2026-63440

cve-icon Redhat

No data.