CVE-2025-21792

MEDIUM EPSS 10.7%
Published Feb 27, 20251y ago · Modified Jun 17, 20261w ago
5.5 CVSS 3.1
Medium
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Published Feb 27, 2025 1y ago
Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: ax25: Fix refcount leak caused by setting SO_BINDTODEVICE sockopt If an AX25 device is bound to a socket by setting the SO_BINDTODEVICE socket option, a refcount leak will occur in ax25_release(). Commit 9fd75b66b8f6 ("ax25: Fix refcount leaks caused by ax25_cb_del()") added decrement of device refcounts in ax25_release(). In order for that to work correctly the refcounts must already be incremented when the device is bound to the socket. An AX25 device can be bound to a socket by either calling ax25_bind() or setting SO_BINDTODEVICE socket option. In both cases the refcounts should be incremented, but in fact it is done only in ax25_bind(). This bug leads to the following issue reported by Syzkaller: ================================================================ refcount_t: decrement hit 0; leaking memory. WARNING: CPU: 1 PID: 5932 at lib/refcount.c:31 refcount_warn_saturate+0x1ed/0x210 lib/refcount.c:31 Modules linked in: CPU: 1 UID: 0 PID: 5932 Comm: syz-executor424 Not tainted 6.13.0-rc4-syzkaller-00110-g4099a71718b0 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:refcount_warn_saturate+0x1ed/0x210 lib/refcount.c:31 Call Trace: <TASK> __refcount_dec include/linux/refcount.h:336 [inline] refcount_dec include/linux/refcount.h:351 [inline] ref_tracker_free+0x710/0x820 lib/ref_tracker.c:236 netdev_tracker_free include/linux/netdevice.h:4156 [inline] netdev_put include/linux/netdevice.h:4173 [inline] netdev_put include/linux/netdevice.h:4169 [inline] ax25_release+0x33f/0xa10 net/ax25/af_ax25.c:1069 __sock_release+0xb0/0x270 net/socket.c:640 sock_close+0x1c/0x30 net/socket.c:1408 ... do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f ... </TASK> ================================================================ Fix the implementation of ax25_setsockopt() by adding increment of refcounts for the new device bound, and decrement of refcounts for the old unbound device.

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
10.7% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Affected Products 11

VendorProductVersionRange
linuxlinux_kernel*≥4.14.277  –  <4.15
linuxlinux_kernel*≥4.19.240  –  <4.20
linuxlinux_kernel*≥5.4.190  –  <5.5
linuxlinux_kernel*≥5.10.112  –  <5.11
linuxlinux_kernel*≥5.15.35  –  <5.16
linuxlinux_kernel*≥5.17.2  –  <6.1.129
linuxlinux_kernel*≥6.2  –  <6.6.79
linuxlinux_kernel*≥6.7  –  <6.12.16
linuxlinux_kernel*≥6.13  –  <6.13.4
linuxlinux_kernel6.14any
linuxlinux_kernel6.14any

References 6

  • git.kernel.org https://git.kernel.org/stable/c/470bda72fda0fcf54300466d70ce2de62f7835d2
    Mailing ListPatch
  • git.kernel.org https://git.kernel.org/stable/c/90056ece99966182dc0e367f3fd2afab46ada847
    Mailing ListPatch
  • git.kernel.org https://git.kernel.org/stable/c/94a0de224ed52eb2ecd4f4cb1b937b674c9fb955
    Mailing ListPatch
  • git.kernel.org https://git.kernel.org/stable/c/b58f7ca86a7b8e480c06e30c5163c5d2f4e24023
    Mailing ListPatch
  • git.kernel.org https://git.kernel.org/stable/c/bca0902e61731a75fc4860c8720168d9f1bae3b6
    Mailing ListPatch
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/470bda72fda0fcf54300466d70ce2de62f7835d2
    Mailing ListPatch
  • git.kernel.org https://git.kernel.org/stable/c/90056ece99966182dc0e367f3fd2afab46ada847
    Mailing ListPatch
  • git.kernel.org https://git.kernel.org/stable/c/94a0de224ed52eb2ecd4f4cb1b937b674c9fb955
    Mailing ListPatch
  • git.kernel.org https://git.kernel.org/stable/c/b58f7ca86a7b8e480c06e30c5163c5d2f4e24023
    Mailing ListPatch
  • git.kernel.org https://git.kernel.org/stable/c/bca0902e61731a75fc4860c8720168d9f1bae3b6
    Mailing ListPatch