CVE-2026-88880 in Renovate
Summary
by MITRE • 09/10/2026
Renovate before 44.11.3 fails to validate Link header destinations when following GitLab server pagination, allowing malicious servers to redirect credential-bearing requests. Attackers controlling a compromised GitLab server can specify a Link header pointing to attacker-controlled infrastructure to exfiltrate authentication credentials.
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Analysis
by VulDB Data Team • 09/10/2026
The vulnerability identified in Renovate versions prior to 44.11.3 stems from an insufficient validation of HTTP response headers, specifically the Link header used for pagination when interacting with GitLab servers. This flaw allows a malicious or compromised server to manipulate the redirect behavior of the client application during data retrieval operations. When Renovate fetches repository information or other resources from a GitLab instance that supports paginated responses, it relies on the Link header provided by the server to determine subsequent URLs for fetching additional pages of results. The software fails to adequately verify whether these destination URLs are within an expected domain or scope, thereby trusting arbitrary values supplied in this header without sufficient scrutiny regarding their origin or intent.
This lack of validation creates a pathway for credential exfiltration through open redirect mechanisms. An attacker who controls a compromised GitLab server can inject a malicious Link header containing a URL pointing to infrastructure under the attacker's control. As Renovate processes these pagination links, it follows them blindly, sending HTTP requests that include authentication credentials such as access tokens or cookies in the headers of subsequent requests directed at the attacker-controlled endpoint. This effectively bypasses standard security controls because the redirection is initiated by the application itself based on trusted server responses rather than direct user interaction with a suspicious link.
The operational impact of this vulnerability is significant for organizations relying on Renovate to manage dependency updates across their codebases. If an internal GitLab instance or a third-party repository host is compromised, attackers can leverage this flaw to harvest sensitive authentication tokens from any developer machine running the affected version of Renovate. These stolen credentials can then be used to access private repositories, inject malicious dependencies into projects, or pivot further within the corporate network. The attack vector relies on social engineering aspects indirectly, as it requires the victim's system to interact with a compromised service that appears legitimate but contains hidden malicious instructions in its response headers.
From a classification perspective, this issue aligns with CWE-601, URL Redirection to Untrusted Site (Open Redirect), and specifically relates to CWE-942, Permissiveness of Cross-Origin Resource Sharing, although the primary failure is in header validation rather than CORS policy configuration. In terms of the MITRE ATT&CK framework, this vulnerability facilitates Credential Access via Tactic 1078, Valid Accounts, by allowing attackers to harvest existing credentials through automated requests triggered during normal software operation. It also touches upon Supply Chain Compromise if the compromised GitLab server is part of a trusted dependency update pipeline.
To mitigate this risk, organizations must upgrade Renovate to version 44.11.3 or later where these validation checks have been implemented. Until an upgrade can be performed, administrators should monitor network traffic for unusual outbound connections from systems running Renovate and ensure that internal GitLab instances are hardened against compromise through strict access controls and regular security audits. Additionally, implementing egress filtering rules to restrict outbound HTTP requests to known trusted domains can provide a layer of defense in depth, preventing the exfiltration of credentials even if the application logic fails to validate the Link header correctly.