CVE-2023-25820
Nextcloud Server 21.0.0 – 21.0.9
Raw vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:LSummary
CVE-2023-25820 is a medium-severity Improper Restriction of Excessive Authentication Attempts (CWE-307) vulnerability in Nextcloud Nextcloud Server. Its CVSS base score is 4.2 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Brute Force (T1110); ranked at the 15th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-29712
Vulnerability Data
Nextcloud Server is the file server software for Nextcloud, a self-hosted productivity platform, and Nextcloud Enterprise Server is the enterprise version of the file server software. In Nextcloud Server versions 25.0.x prior to 25.0.5 and versions 24.0.x prior to 24.0.10…
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as well as Nextcloud Enterprise Server versions 25.0.x prior to 25.0.4, 24.0.x prior to 24.0.10, 23.0.x prior to 23.0.12.5, 22.x prior to 22.2.0.10, and 21.x prior to 21.0.9.10, when an attacker gets access to an already logged in user session they can then brute force the password on the confirmation endpoint. Nextcloud Server should upgraded to 24.0.10 or 25.0.4 and Nextcloud Enterprise Server should upgraded to 21.0.9.10, 22.2.10.10, 23.0.12.5, 24.0.10, or 25.0.4 to receive a patch. No known workarounds are available.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 2 hardening rules · 1 OS baseline
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Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
This control directly enforces limits on consecutive invalid logon attempts and automatic response (e.g., lockout) to prevent brute-force exploitation of authentication mechanisms.
Specific conditions can include excessive failed attempts, triggering stronger authentication that restricts brute-force exploitation.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Authentication enforcement directly includes lockout, throttling, and MFA policies that prevent brute-force attempts.
Behavioral monitoring of authentication activity can detect excessive failed attempts after they occur.
Generating auth logs enables later detection or forensics but does not itself restrict attempts.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
CAPTCHA, account lock-out after repeated failures, and alerts on excessive attempts directly stop automated brute-force guessing of credentials.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
RHEL 7 (2 rules)
- V-204427 The Red Hat Enterprise Linux operating system must be configured to lock accounts for a minimum of 15 minutes after three unsuccessful logon attempts within a 15-minute timeframe. prevents CWE-307
- V-204428 The Red Hat Enterprise Linux operating system must lock the associated account after three unsuccessful root logon attempts are made within a 15-minute period. prevents CWE-307