Answer in brief
CVE-2026-63440 records a Medium severity (CVSS 5.9) vulnerability in 2FAuth: Authenticated SSRF via DNS rebinding in the otpauth image= icon fetch (validate-then-fetch TOCTOU). The current sources do not mark it as known exploited. The current feed maps Bubka/2FAuth (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.9. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Bubka/2FAuth (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Bubka/2FAuthgeneric | <8.0.0 | 8.0.0 |
Published upstream
Nov 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 6, 2026
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.
Quoted source text, attributed separately from HOL analysis.