Open redirect via OIDC in Nextcloud 6.1.08.2.1
CVE-2026-45278 Published on June 1, 2026
Nextcloud: Open Redirect in user_oidc login flow via protocol-relative URL bypass
Nextcloud is an open source content collaboration platform. From version 6.1.0 to before version 8.2.2, an attacker can craft links that would redirect users to another website, when the victim uses the attackers link to log in via user OIDC. This issue has been patched in version 8.2.2.
Vulnerability Analysis
CVE-2026-45278 is exploitable with local system access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, with no impact on integrity, and no impact on availability.
Weakness Type
What is an Open Redirect Vulnerability?
A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks. An http parameter may contain a URL value and could cause the web application to redirect the request to the specified URL. By modifying the URL value to a malicious site, an attacker may successfully launch a phishing scam and steal user credentials. Because the server name in the modified link is identical to the original site, phishing attempts have a more trustworthy appearance.
CVE-2026-45278 has been classified to as an Open Redirect vulnerability or weakness.