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Vulnerabilities

Vulnerability · CVE-2025-37949

In the Linux kernel, the following vulnerability has been resolved: xenbus: Use kref to track req lifetime Marek reported seeing a NULL pointer fault in the xenbus_thread callstack

Published May 20, 2025 · catalog updated Oct 15, 2026 · Linux Linux

Check if you run it

No confirmed exploitation is on record for CVE-2025-37949. EPSS is 0.24%. Act only if a listed version of Linux Linux is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.24%
Remediation
Version ranges on file
Affected products
cpe debian/debian linux · cpe linux/linux kernel · vendor Linux Linux fd8aa9095a95c02dcc35540a263267c29b8fda9d <f1bcac367bc95631afbb918348f30dec887d0e1b

In the Linux kernel, the following vulnerability has been resolved: xenbus: Use kref to track req lifetime Marek reported seeing a NULL pointer fault in the xenbus_thread callstack: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: e030:__wake_up_common+0x4c/0x180 Call Trace: __wake_up_common_lock+0x82/0xd0 process_msg+0x18e/0x2f0 xenbus_thread+0x165/0x1c0 process_msg+0x18e is req->cb(req). req->cb is set to xs_wake_up(), a thin wrapper around wake_up(), or xenbus_dev_queue_reply(). It seems like it was xs_wake_up() in this case. It seems like req may have woken up the xs_wait_for_reply(), which kfree()ed the req. When xenbus_thread resumes, it faults on the zero-ed data. Linux Device Drivers 2nd edition states: "Normally, a wake_up call can cause an immediate reschedule to happen, meaning that other processes might run before wake_up returns." ... which would match the behaviour observed. Change to keeping two krefs on each request. One for the caller, and one for xenbus_thread. Each will kref_put() when finished, and the last will free it. This use of kref matches the description in Documentation/core-api/kref.rst

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.

  • cpe debian/debian linux11.0
  • cpe linux/linux kernel6.15
  • vendor Linux Linux fd8aa9095a95c02dcc35540a263267c29b8fda9d <f1bcac367bc95631afbb918348f30dec887d0e1bfd8aa9095a95c02dcc35540a263267c29b8fda9d <f1bcac367bc95631afbb918348f30dec887d0e1b

How to fix CVE-2025-37949

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-2025-37949. EPSS is 0.24%. Act only if a listed version of Linux Linux is installed.

Which versions are affected?

Compare what you have installed with debian/debian linux 11.0; linux/linux kernel 6.15; Linux Linux fd8aa9095a95c02dcc35540a263267c29b8fda9d <f1bcac367bc95631afbb918348f30dec887d0e1b fd8aa9095a95c02dcc35540a263267c29b8fda9d <f1bcac367bc95631afbb918348f30dec887d0e1b. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-476: NULL Pointer Dereference. EPSS 0.24%. 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. May 20, 2025 · NIST NVD

    Detected

    In the Linux kernel, the following vulnerability has been resolved: xenbus: Use kref to track req lifetime Marek reported seeing a NULL pointer fault in the xenbus_thread callstack: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: e030:__wake_up_common+0x4c/0x180 Call Trace: __wake_up_common_lock+0x82/0xd0 process_msg+0x18e/0x2f0 xenbus_thread+0x165/0x1c0 process_msg+0x18e is r

  2. Oct 15, 2026 · NIST NVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: xenbus: Use kref to track req lifetime Marek reported seeing a NULL pointer fault in the xenbus_thread callstack: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: e030:__wake_up_common+0x4c/0x180 Call Trace: __wake_up_common_lock+0x82/0xd0 process_msg+0x18e/0x2f0 xenbus_thread+0x165/0x1c0 process_msg+0x18e is r

Sources

  • CVE.orgVulnerability recordCVE-2025-37949

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-37949

    30-day exploitation probability 0.2%

    first.org
  • EUVDVulnerability recordEUVD-2025-15894

    In the Linux kernel, the following vulnerability has been resolved: xenbus: Use kref to track req lifetime Marek reported seeing a NULL pointer fault in the xenbus_thread callstack: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: e030:__wake_up_common+0x4c/0x

    euvd.enisa.europa.eu
  • NIST NVDVulnerability recordCVE-2025-37949

    In the Linux kernel, the following vulnerability has been resolved: xenbus: Use kref to track req lifetime Marek reported seeing a NULL pointer fault in the xenbus_thread callstack: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: e030:__wake_up_common+0x4c/

    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.