The NFS client implementation in the kernel in Red Hat Enterprise Linux (RHEL) 3, when a filesystem is mounted with the noacl option, checks permissions for the open system call via vfs_permission (mode bits) data rather than an NFS ACCESS call to the server, which allows local client processes to obtain a false success status from open calls that the server would deny, and possibly obtain sensitive information about file permissions on the server, as demonstrated in a root_squash environment. NOTE: it is uncertain whether any scenarios involving this issue cross privilege boundaries.
CVSS Severity (version 2.0):
Impact Subscore: 2.9
Exploitability Subscore: 3.4
CVSS Version 2 Metrics:
Access Vector: Locally exploitable
Access Complexity: Medium
Authentication: Not required to exploit
Impact Type: Allows unauthorized disclosure of information
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Vulnerable software and versions