Nextcloud user_oidc <1.3: OIDC State Token Bypass
CVE-2023-28848 Published on April 4, 2023
CSRF protection on user_oidc login returned the expected token in case of an error
user_oidc is the OIDC connect user backend for Nextcloud, an open source collaboration platform. A vulnerability in versions 1.0.0 until 1.3.0 effectively allowed an attacker to bypass the state protection as they could just copy the expected state token from the first request to their second request. Users should upgrade user_oidc to 1.3.0 to receive a patch for the issue. No known workarounds are available.
Vulnerability Analysis
CVE-2023-28848 is exploitable with network access, requires user interaction and user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Weakness Type
What is a Session Riding Vulnerability?
The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request. When a web server is designed to receive a request from a client without any mechanism for verifying that it was intentionally sent, then it might be possible for an attacker to trick a client into making an unintentional request to the web server which will be treated as an authentic request. This can be done via a URL, image load, XMLHttpRequest, etc. and can result in exposure of data or unintended code execution.
CVE-2023-28848 has been classified to as a Session Riding vulnerability or weakness.
Products Associated with CVE-2023-28848
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Affected Versions
nextcloud security-advisories Version >= 1.0.0, < 1.3.0 is affected by CVE-2023-28848Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.