AliasVault’s favicon extractor performs a DNS resolution when validating a supplied hostname but then uses a second lookup during the actual connection. By controlling an authoritative DNS server, an attacker can return a public address during the validation step and a private, internal address during the connection step. This forces a publicly reachable self‑hosted AliasVault instance to issue HTTP or HTTPS requests to internal hosts on ports 80 or 443. The server returns a Base64‑encoded image when the request is successful, and for other responses timing or error information can be used for limited internal‑network reconnaissance.

All AliasVault server deployments running any version before 0.30.3 are vulnerable. This includes the aliasvault:aliasvault, aliasvault:ghcr.io/aliasvault/aliasvault, aliasvault:ghcr.io/aliasvault/api, and aliasvault:ghcr.io/lanedirt/aliasvault-api container images, when the instance is publicly reachable and public registration is enabled. The web user interface, browser extensions, and mobile apps are not affected.

The CVSS score of 6.3 indicates a moderate severity. The EPSS score is below 1 %, signifying a low probability of exploitation at the current time, and the vulnerability is not listed in CISA’s KEV catalog. Attackers must have a publicly reachable self‑hosted AliasVault instance with public registration enabled, an authenticated account, control over an authoritative DNS server that allows rebinding, and a resolver that permits rebinding. When all conditions are met, the server can be coerced into contacting internal hosts, potentially leaking internal addresses, timing information, or data from internal services, and providing a foothold for further lateral movement.