link-preview-js DNS Rebinding SSRF Bypass / Incomplete Fix for CVE-2026-43897

The existing advisory GHSA-4gp8-rjrq-ch6q / CVE-2026-43897 states that the SSRF issue was fixed in 4.0.1. However, 4.0.3 remains bypassable when the documented resolveDNSHost mitigation is used. Root cause: The library validates one resolved IP address through resolveDNSHost, but later performs fetch() against the original hostname without pinning the connection to the validated IP. An attacker-controlled DNS server can return a public IP during validation and a loopback/internal IP during the final connection. Impact: This allows an attacker to bypass the documented SSRF mitigation and make the server-side fetch reach loopback or internal addresses under DNS rebinding conditions. This appears to be either an incomplete fix for CVE-2026-43897 or a new DNS rebinding SSRF bypass affecting the latest version. The PoC was reproduced in a local-only controlled environment to avoid targeting production or third-party systems. Evidence and reproduction details can be provided privately.

Source published

2 Sep 2026 21:29:57 UTC

Source modified

2 Sep 2026 21:45:09 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Publisher rating · HIGH