CVE-2026-45278 Nextcloud: Open Redirect in user_oidc login flow via protocol-relative URL bypass
Attackers can redirect users to malicious sites during OIDC login via crafted links, potentially facilitating phishing attacks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-45278?
CVE-2026-45278 is a low-severity vulnerability in nextcloud security-advisories, published on 1 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
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.
Weakness: CWE-601
Which versions are affected by CVE-2026-45278?
It affects 1 product.
Products include Nextcloud User Oidc.
How do I fix CVE-2026-45278?
No fix has been published for CVE-2026-45278 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-45278 being exploited?
There is no known exploitation of CVE-2026-45278 in the wild and no public exploit code.
Other vulnerabilities in nextcloud security-advisories
- CVE-2023-32074 Nextcloud user_oidc app is missing brute force protection
- CVE-2024-37312 Nextcloud user_oidc app's ID4me feature is available even when disabled
- CVE-2024-37886 Nextcloud user_oidc's ID4me does not validate signature or expiration
- CVE-2023-39953 Issuer not verified from obtained token in user_oidc
- CVE-2023-28848 CSRF protection on user_oidc login returned the expected token in case of an error
Sources
Also known as GHSA-8wjr-5cg8-4w73.