CVE-2025-37949

MEDIUM EPSS 5.8%

Published May 20, 20251y ago · Modified Jun 17, 20261w ago

5.5 CVSS 3.1

Medium

Published May 20, 2025 1y ago

Last Modified Jun 17, 2026 1w ago

Description

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: <TASK> __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

CVSS Details

Base Score

5.5

Exploitability

1.8

Impact

3.6

Vector string

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector Local

Attack Complexity Low

Privileges Required Low

User Interaction None

Scope Unchanged

Confidentiality None

Integrity None

Availability High

Threat Intelligence

EPSS Exploit Probability

5.8% percentile

Exploit & Patch Status

No Known Exploit

Patch Available

Weaknesses 1

CWE-476 NULL Pointer Dereference Memory Safety

Affected Products 13

Vendor	Product	Version	Range
linux	linux_kernel	*	≥4.11 – <5.4.294
linux	linux_kernel	*	≥5.5 – <5.10.238
linux	linux_kernel	*	≥5.11 – <5.15.183
linux	linux_kernel	*	≥5.16 – <6.1.139
linux	linux_kernel	*	≥6.2 – <6.6.91
linux	linux_kernel	*	≥6.7 – <6.12.29
linux	linux_kernel	*	≥6.13 – <6.14.7
linux	linux_kernel	6.15	any
linux	linux_kernel	6.15	any
linux	linux_kernel	6.15	any
linux	linux_kernel	6.15	any
linux	linux_kernel	6.15	any
debian	debian_linux	11.0	any

References 10

git.kernel.org https://git.kernel.org/stable/c/0e94a246bb6d9538010b6c02d2b1d4717a97b2e5

Patch
git.kernel.org https://git.kernel.org/stable/c/1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27

Patch
git.kernel.org https://git.kernel.org/stable/c/2466b0f66795c3c426cacc8998499f38031dbb59

Patch
git.kernel.org https://git.kernel.org/stable/c/4d260a5558df4650eb87bc41b2c9ac2d6b2ba447

Patch
git.kernel.org https://git.kernel.org/stable/c/8b02f85e84dc6f7c150cef40ddb69af5a25659e5

Patch
git.kernel.org https://git.kernel.org/stable/c/8e9c8a0393b5f85f1820c565ab8105660f4e8f92

Patch
git.kernel.org https://git.kernel.org/stable/c/cbfaf46b88a4c01b64c4186cdccd766c19ae644c

Patch
git.kernel.org https://git.kernel.org/stable/c/f1bcac367bc95631afbb918348f30dec887d0e1b

Patch
lists.debian.org https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html

Third Party Advisory
lists.debian.org https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html

Third Party Advisory

Remediation

git.kernel.org https://git.kernel.org/stable/c/0e94a246bb6d9538010b6c02d2b1d4717a97b2e5

Patch
git.kernel.org https://git.kernel.org/stable/c/1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27

Patch
git.kernel.org https://git.kernel.org/stable/c/2466b0f66795c3c426cacc8998499f38031dbb59

Patch
git.kernel.org https://git.kernel.org/stable/c/4d260a5558df4650eb87bc41b2c9ac2d6b2ba447

Patch
git.kernel.org https://git.kernel.org/stable/c/8b02f85e84dc6f7c150cef40ddb69af5a25659e5

Patch
git.kernel.org https://git.kernel.org/stable/c/8e9c8a0393b5f85f1820c565ab8105660f4e8f92

Patch
git.kernel.org https://git.kernel.org/stable/c/cbfaf46b88a4c01b64c4186cdccd766c19ae644c

Patch
git.kernel.org https://git.kernel.org/stable/c/f1bcac367bc95631afbb918348f30dec887d0e1b

Patch