Is CVE-2026-63440 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-63440 being exploited in the wild.

How severe is CVE-2026-63440?

Medium severity, with a CVSS score of 5.9, published 6 November 2026.

Is there a fix for CVE-2026-63440?

Yes: fixed in 8.0.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-63440 attacked?

It is attacked over the network, in a web application.

Am I affected by CVE-2026-63440?

Check whether you run Bubka 2FAuth at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-63440: 2FAuth SSRF via DNS rebinding in otpauth image fetch

CVE-2026-63440 · Severity: medium · CVSS 5.9 · Published 2026-11-06

2FAuth is a web application that manages two-factor authentication (2FA) accounts and generates security codes. When external otpauth image fetching is enabled, an authenticated attacker with control over DNS can bypass security checks to reach internal network addresses, cloud metadata endpoints, or localhost, potentially exposing sensitive data or internal services. The vulnerability exploits a time-of-check-to-time-of-use (TOCTOU) flaw in hostname validation.

Technologies: Bubka 2FAuth. Vendors: Bubka.

Quick answers

Is CVE-2026-63440 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-63440 being exploited in the wild.
How severe is CVE-2026-63440?: Medium severity, with a CVSS score of 5.9, published 6 November 2026.
Which products and versions are affected?: Bubka 2FAuth prior to 8.0.0.
Is there a fix for CVE-2026-63440?: Yes: fixed in 8.0.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-63440 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-63440?: Check whether you run Bubka 2FAuth at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: 8.0.0

Technical details

The vulnerability is a Server-Side Request Forgery (SSRF) via DNS rebinding in the otpauth image-fetch functionality. The vulnerable code validates a hostname through ValidatesUrls::isExternalHost() but then resolves the same hostname again when making the HTTP request via IconService::storeRemoteImage(). An attacker 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 access loopback, private-network, link-local, or cloud metadata endpoints. The fix pins the validated IP address to prevent re-resolution.

Affected products

Bubka 2FAuth prior to 8.0.0

Timeline

2026-11-06: disclosed
2026-07-01: patched

References

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