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Fencer Vulns
high 7.8

CVE-2025-22109 json

ax25: Remove broken autobind

published 2025-04-16 18 mo ago modified 2026-10-30 10 d ago also EUVD-2025-11176

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 16%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

ax25: Remove broken autobind

Binding AX25 socket by using the autobind feature leads to memory leaks in ax25_connect() and also refcount leaks in ax25_release(). Memory leak was detected with kmemleak:

================================================================ unreferenced object 0xffff8880253cd680 (size 96): backtrace: __kmalloc_node_track_caller_noprof (./include/linux/kmemleak.h:43) kmemdup_noprof (mm/util.c:136) ax25_rt_autobind (net/ax25/ax25_route.c:428) ax25_connect (net/ax25/af_ax25.c:1282) __sys_connect_file (net/socket.c:2045) __sys_connect (net/socket.c:2064) __x64_sys_connect (net/socket.c:2067) do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) ================================================================

When socket is bound, refcounts must be incremented the way it is done in ax25_bind() and ax25_setsockopt() (SO_BINDTODEVICE). In case of autobind, the refcounts are not incremented.

This bug leads to the following issue reported by Syzkaller:

================================================================ ax25_connect(): syz-executor318 uses autobind, please contact jreuter@yaina.de ------------[ cut here ]------------ refcount_t: decrement hit 0; leaking memory. WARNING: CPU: 0 PID: 5317 at lib/refcount.c:31 refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:31 Modules linked in: CPU: 0 UID: 0 PID: 5317 Comm: syz-executor318 Not tainted 6.14.0-rc4-syzkaller-00278-gece144f151ac #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+0xfa/0x1d0 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+0x6af/0x7e0 lib/ref_tracker.c:236 netdev_tracker_free include/linux/netdevice.h:4302 [inline] netdev_put include/linux/netdevice.h:4319 [inline] ax25_release+0x368/0x960 net/ax25/af_ax25.c:1080 __sock_release net/socket.c:647 [inline] sock_close+0xbc/0x240 net/socket.c:1398 __fput+0x3e9/0x9f0 fs/file_table.c:464 __do_sys_close fs/open.c:1580 [inline] __se_sys_close fs/open.c:1565 [inline] __x64_sys_close+0x7f/0x110 fs/open.c:1565 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f ... </TASK> ================================================================

Considering the issues above and the comments left in the code that say: "check if we can remove this feature. It is broken."; "autobinding in this may or may not work"; - it is better to completely remove this feature than to fix it because it is broken and leads to various kinds of memory bugs.

Now calling connect() without first binding socket will result in an error (-EINVAL). Userspace software that relies on the autobind feature might get broken. However, this feature does not seem widely used with this specific driver as it was not reliable at any point of time, and it is already broken anyway. E.g. ax25-tools and ax25-apps packages for popular distributions do not use the autobind feature for AF_AX25.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Patch / fix

  • Linux Linux 6.1.191, 6.6.160, 6.12.114, 6.14.2, 6.15
  • linux Debian 13 6.12.115-2
  • linux Debian 14 6.16.3-1

debian advisories DEBIAN-CVE-2025-22109

  • linux-nvidia-tegra Ubuntu 24.04 LTS 6.8.0-1035.38

ubuntu advisories UBUNTU-CVE-2025-22109

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-rt Real Time Module 15 SP7 6.4.0-150700.7.3.1
  • kernel-syms-rt Real Time Module 15 SP7 6.4.0-150700.7.3.1
  • kernel-rt_debug Real Time Module 15 SP7 6.4.0-150700.7.3.1
  • kernel-source-rt Real Time Module 15 SP7 6.4.0-150700.7.3.1
  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
  • kernel-syms-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
  • kernel-source-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
  • kernel-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.39.1

suse advisories SUSE-SU-2025:01972-1SUSE-SU-2025:01967-1SUSE-SU-2025:01964-1SUSE-SU-2025:01951-1SUSE-SU-2025:01919-1SUSE-SU-2025:01707-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-22109 updated

kernel: ax25: Remove broken autobind

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-401 Missing Release of Memory after Effective Lifetime
Technology feeds

References

Sources

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