CVE-2026-88881: Renovate before 44.11.3 Credential Exfiltration via Link Header

Renovate, a dependency update tool, follows pagination links supplied by the GitHub server in the HTTP `Link` header when interacting with GitHub.com, GitHub Enterprise Cloud, or GitHub Enterprise Server, and sends the credentials configured for that host to the URL given as the 'next' page. Because the pagination URL is not validated against the host originally contacted, a malicious or compromised GitHub server can return a `Link` header pointing to an attacker-controlled host and cause Renovate to disclose those credentials to it. Exploitation requires that the GitHub server Renovate talks to (as the repository host or as a datasource such as github-releases, github-tags, or git-refs) is already malicious or compromised. The issue is fixed in renovate 44.11.3 (npm and renovate/renovate container images), Mend Renovate CE/EE images and the mend-renovate-ce helm chart 15.4.0, and the mend-renovate-enterprise-edition helm chart 10.4.0. There is no workaround; the pre-existing RENOVATE_X_REBASE_PAGINATION_LINKS option disables the new host check and should only be used with servers that intentionally use different pagination hosts.