Authentication bypass via missing token issuer validation
Published Aug 10, 2023 · Updated Oct 3, 2024
Authentication bypass in Nextcloud user_oidc 1.0.0 through 1.3.2 allows remote attackers to gain access with a known token. LoginController and SelfEncodedValidator accepted ID and bearer tokens without comparing the iss claim with the configured provider discovery issuer. Exploitation requires a man-in-the-middle position in the OIDC flow and access to a known or corrupted token, granting access as the token subject.
Summary
What happened
Authentication bypass in Nextcloud user_oidc 1.0.0 through 1.3.2 allows remote attackers to gain access with a known token. LoginController and SelfEncodedValidator accepted ID and bearer tokens without comparing the iss claim with the configured provider discovery issuer. Exploitation requires a man-in-the-middle position in the OIDC flow and access to a known or corrupted token, granting access as the token subject.
The record
- CVE
- CVE-2023-39953
- Published
- Aug 10, 2023
- Updated
- Oct 3, 2024
- Vendor
- Nextcloud GmbH
- Product
- Security Advisories
- Classifications
- CWE-303, T1550.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 10, 2023CVE publishedPublication date reported by the CVE source.
- Oct 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=>= 1.0.0, < 1.3.3
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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