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Bruteforce protection can be bypassed with misconfigured proxy

Moderate
nickvergessen published GHSA-5j2p-q736-hw98 Dec 18, 2023

Package

Server (Nextcloud)

Affected versions

>= 26.0.0, >= 27.0.0

Patched versions

26.0.9, 27.1.4
Server (Nextcloud Enterprise)
>= 23.0.0, >= 24.0.0, >= 25.0.0, >= 26.0.0, >= 27.0.0
23.0.12.13, 24.0.12.9, 25.0.13.4, 26.0.9, 27.1.4

Description

Impact

When a (reverse) proxy is configured as trusted proxy the server could be tricked into reading a wrong remote address for an attacker, allowing them executing authentication attempts than intended.

Patches

It is recommended that the Nextcloud Server is upgraded to 26.0.9 or 27.1.4
It is recommended that the Nextcloud Enterprise Server is upgraded to 23.0.12.13, 24.0.12.9, 25.0.13.4, 26.0.9 or 27.1.4

Workarounds

  • No workaround available

References

For more information

If you have any questions or comments about this advisory:

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVE ID

CVE-2023-49792

Weaknesses

Credits