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Linux KernelOperating system · Linux

CVE-2025-22109

MEDIUM · 5.5 CVSS v3.1 Published 2025-04-16
Fix available
A fix is available. Upgrade to 6.14.2 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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 [email protected] ------------[ 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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-401

Allocated memory is never released on some path, so a long-running service or a repeatedly triggered request steadily consumes memory until performance degrades or the process crashes. Attackers exploit it by simply driving the leaking path. Remediation is pairing every allocation with a release and using ownership patterns or tooling to catch what leaks.

General guidance for the memory leak class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 2.6.13, < 6.14.2= 2.6.12

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.14.2 or later
Fixed in 6.14.2
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux Kernel 6.14.2 or later stable release

  1. Identify systems running Linux kernel versions < 6.14.2 that use AF_AX25 sockets
  2. Plan kernel upgrade to version 6.14.2 or later
  3. Apply the kernel update via distribution package manager or compile from source
  4. Reboot systems to load the fixed kernel
  5. Verify kernel version post-reboot with 'uname -r'
  6. Test AX25 functionality to ensure normal operation
  7. Note: Review any custom userspace applications that may rely on the autobind feature - they will need to explicitly call bind() before connect() as the autobind behavior is now removed
Caveat Applications relying on the AX25 autobind feature (connecting without explicit bind) will break and receive -EINVAL errors; they must be updated to call bind() before connect()

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-22109 in production — separate from our analysis above.

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