link-preview-js DNS Rebinding SSRF Bypass / Incomplete Fix for CVE-2026-43897
Link Preview JS extracts web links information. Prior to 4.0.4, the resolveDNSHost mitigation in index.ts validates one resolved IP address but fetches the original hostname, allowing an attacker-controlled DNS server to return a public address during validation and a loopback or internal address during the final connection. This DNS rebinding condition bypasses the SSRF protection and can cause the server-side preview fetch to reach internal HTTP resources. Redirect handling is affected by the same validation-to-fetch mismatch. This issue is fixed in version 4.0.4.
Link Preview JS: vunerable to IPv6 and internal loopback attacks
Link Preview JS extracts web links information. Prior to 4.0.1, the library did not check for IPv6 loopback attacks. There was also a DNS attack, where an address could be resolved into an internal IP. This could cause internal data leaks. This vulnerability is fixed in 4.0.1.
The package link-preview-js before 2.1.16 are vulnerable to Server-side Request Forgery (SSRF) which allows attackers to send arbitrary requests to the local network and read the response. This is due to flawed DNS rebinding protection.