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Vulnerabilities

Vulnerability · CVE-2025-40362

In the Linux kernel, the following vulnerability has been resolved: ceph: fix multifs mds auth caps issue The mds auth caps check should also validate the fsname along…

Published Dec 16, 2025 · catalog updated Oct 15, 2026 · the affected product

Check if you run it

No confirmed exploitation is on record for CVE-2025-40362. EPSS is 0.16%. Act only if a listed version of the affected product is installed.

Gaps on this record

  • No plain product name is stored. The page cannot tell you which product to check.
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.16%
Remediation
Not established
Affected products
See sources for product scope

In the Linux kernel, the following vulnerability has been resolved: ceph: fix multifs mds auth caps issue The mds auth caps check should also validate the fsname along with the associated caps. Not doing so would result in applying the mds auth caps of one fs on to the other fs in a multifs ceph cluster. The bug causes multiple issues w.r.t user authentication, following is one such example. Steps to Reproduce (on vstart cluster): 1. Create two file systems in a cluster, say 'fsname1' and 'fsname2' 2. Authorize read only permission to the user 'client.usr' on fs 'fsname1' $ceph fs authorize fsname1 client.usr / r 3. Authorize read and write permission to the same user 'client.usr' on fs 'fsname2' $ceph fs authorize fsname2 client.usr / rw 4. Update the keyring $ceph auth get client.usr >> ./keyring With above permssions for the user 'client.usr', following is the expectation. a. The 'client.usr' should be able to only read the contents and not allowed to create or delete files on file system 'fsname1'. b. The 'client.usr' should be able to read/write on file system 'fsname2'. But, with this bug, the 'client.usr' is allowed to read/write on file system 'fsname1'. See below. 5. Mount the file system 'fsname1' with the user 'client.usr' $sudo bin/mount.ceph usr@.fsname1=/ /kmnt_fsname1_usr/ 6. Try creating a file on file system 'fsname1' with user 'client.usr'. This should fail but passes with this bug. $touch /kmnt_fsname1_usr/file1 7. Mount the file system 'fsname1' with the user 'client.admin' and create a file. $sudo bin/mount.ceph admin@.fsname1=/ /kmnt_fsname1_admin $echo "data" > /kmnt_fsname1_admin/admin_file1 8. Try removing an existing file on file system 'fsname1' with the user 'client.usr'. This shoudn't succeed but succeeds with the bug. $rm -f /kmnt_fsname1_usr/admin_file1 For more information, please take a look at the corresponding mds/fuse patch and tests added by looking into the tracker mentioned below. v2: Fix a possible null dereference in doutc v3

No affected version ranges are stored yet. Use the vendor advisory before you decide this record does not apply.

How to fix CVE-2025-40362

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-40362. EPSS is 0.16%. Act only if a listed version of the affected product is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.16%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Dec 16, 2025 · NIST NVD

    Detected

    In the Linux kernel, the following vulnerability has been resolved: ceph: fix multifs mds auth caps issue The mds auth caps check should also validate the fsname along with the associated caps. Not doing so would result in applying the mds auth caps of one fs on to the other fs in a multifs ceph cluster. The bug causes multiple issues w.r.t user authentication, following is one such example. Steps

  2. Oct 14, 2026 · NIST NVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: ceph: fix multifs mds auth caps issue The mds auth caps check should also validate the fsname along with the associated caps. Not doing so would result in applying the mds auth caps of one fs on to the other fs in a multifs ceph cluster. The bug causes multiple issues w.r.t user authentication, following is one such example. Steps

  3. Oct 15, 2026 · NIST NVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: ceph: fix multifs mds auth caps issue The mds auth caps check should also validate the fsname along with the associated caps. Not doing so would result in applying the mds auth caps of one fs on to the other fs in a multifs ceph cluster. The bug causes multiple issues w.r.t user authentication, following is one such example. Steps

Sources

  • CVE.orgVulnerability recordCVE-2025-40362

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-40362

    30-day exploitation probability 0.2%

    first.org
  • NIST NVDVulnerability recordCVE-2025-40362

    In the Linux kernel, the following vulnerability has been resolved: ceph: fix multifs mds auth caps issue The mds auth caps check should also validate the fsname along with the associated caps. Not doing so would result in applying the mds auth caps of one fs on to the other fs

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.