ksmbd: fix maximum allowed access checks
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 6.6.160, 6.12.114, 6.18.57, 7.2.6
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix maximum allowed access checks The DACL permission check looks for an ACE matching the current user and falls back to the Everyone ACE. It does not consider an Authenticated Users ACE, even though an authenticated session is a member of that well-known group. As a result, opening a file whose access is granted through S-1-5-11 can incorrectly fail with STATUS_ACCESS_DENIED. Treat an Authenticated Users ACE as a fallback entry alongside Everyone. The maximal access calculation also combines access masks from every ACE, regardless of whether its SID applies to the current user. This can grant rights belonging to an unrelated principal. Process only ACEs applying to the user, Everyone, or Authenticated Users, and accumulate allowed and denied masks in ACL order. Preserve explicitly requested access bits so they are validated against the resulting maximal mask. When ACCESS_SYSTEM_SECURITY is denied, report STATUS_PRIVILEGE_NOT_HELD instead of the generic STATUS_ACCESS_DENIED. Access to the system ACL requires a security privilege that ksmbd does not grant. For regular files, include FILE_EXECUTE in maximal access when the client requested GENERIC_EXECUTE and the DACL grants the complete file-read set. Keep a direct FILE_EXECUTE request subject to the explicit DACL bit. This matches the POSIX file ACL mapping without broadening specific execute requests. Do not replace rights from an applicable NT ACE with a POSIX ACL entry. The POSIX ACL is only a fallback when no user, Everyone, or Authenticated Users ACE applies; otherwise it can incorrectly broaden the stored DACL. This fixes smb2.maximum_allowed.maximum_allowed.
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
From e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 · fixed in 7c293e83d86cfd38124f51b27882ad631818bf48; From e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 · fixed in 37459edb69c094553026ee48c2cc2acc657f9f43; From e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 · fixed in 28289d880e6d11ae7ac77b81af3312453febf939; From e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 · fixed in 35d5c59fe6b1d9fe43fb14eb384f69ee1a120f9c; From e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 · fixed in cc2f133e80eb2c4a04bfa77a2f207749fe2f516a
- Linux Linux
5.15
- KernelLinux
From 5.15.0 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.114; From 6.13.0 · fixed in 6.18.57; From 6.19.0 · fixed in 7.2.6