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Vulnerabilities

Vulnerability · CVE-2025-37899

Linux Kernel 'sess->user' Object Use‑After‑Free Vulnerability

Published May 20, 2025 · catalog updated Aug 5, 2026 · Linux Linux

Patch now

CVE-2025-37899 is in the CISA known-exploited catalog. Confirm Linux Linux against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Severity
High8.8
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
0.88%
Remediation
Remediation guidance
Affected products
vendor Linux Kernel · vendor Linux Linux 0626e6641f6b467447c81dd7678a69c66f7746cf <d5ec1d79509b3ee01de02c236f096bc050221b7f

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in session logoff The sess->user object can currently be in use by another thread, for example if another connection has sent a session setup request to bind to the session being free'd. The handler for that connection could be in the smb2_sess_setup function which makes use of sess->user.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor Linux Kernelversion unspecified
  • vendor Linux Linux 0626e6641f6b467447c81dd7678a69c66f7746cf <d5ec1d79509b3ee01de02c236f096bc050221b7f0626e6641f6b467447c81dd7678a69c66f7746cf <d5ec1d79509b3ee01de02c236f096bc050221b7f

How to fix CVE-2025-37899

What to do

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

Should you patch?

CVE-2025-37899 is in the CISA known-exploited catalog. Confirm Linux Linux against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Compare what you have installed with Linux Linux 0626e6641f6b467447c81dd7678a69c66f7746cf <d5ec1d79509b3ee01de02c236f096bc050221b7f 0626e6641f6b467447c81dd7678a69c66f7746cf <d5ec1d79509b3ee01de02c236f096bc050221b7f. Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

What should an analyst verify?

No weakness class is stored. EPSS 0.88%. The CISA KEV listing is the exploitation evidence. 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. Oct 9, 2025 · VulnCheck KEV

    Detected

    In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in session logoff The sess->user object can currently be in use by another thread, for example if another connection has sent a session setup request to bind to the session being free'd. The handler for that connection could be in the smb2_sess_setup function which makes use of sess->user.

  2. Oct 9, 2025 · CISA KEV

    Known exploited

    Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

  3. Aug 5, 2026 · EUVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in session logoff The sess->user object can currently be in use by another thread, for example if another connection has sent a session setup request to bind to the session being free'd. The handler for that connection could be in the smb2_sess_setup function which makes use of sess->user.

Sources

  • CVE.orgVulnerability recordCVE-2025-37899

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-37899

    30-day exploitation probability 0.9%

    first.org
  • EUVDVulnerability recordEUVD-2025-15946

    In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in session logoff The sess->user object can currently be in use by another thread, for example if another connection has sent a session setup request to bind to the session being free'd.

    euvd.enisa.europa.eu
  • VulnCheck KEVConfirmed exploitationCVE-2025-37899

    In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in session logoff The sess->user object can currently be in use by another thread, for example if another connection has sent a session setup request to bind to the session being free'd.

    vulncheck.com

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.