CVE-2025-21792 Affecting kernel-obs-build package, versions <6.4.0-150600.23.50.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-SLES156-KERNELOBSBUILD-10225325
- published22 May 2025
- disclosed21 May 2025
Introduced: 21 May 2025
NewCVE-2025-21792 (opens in a new tab)How to fix?
Upgrade SLES:15.6 kernel-obs-build to version 6.4.0-150600.23.50.1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-obs-build package and not the kernel-obs-build package as distributed by SLES.
See How to fix? for SLES:15.6 relevant fixed versions and status.
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.
References
- https://www.suse.com/security/cve/CVE-2025-21792.html
- https://bugzilla.suse.com/1238745
- https://git.kernel.org/stable/c/470bda72fda0fcf54300466d70ce2de62f7835d2
- https://git.kernel.org/stable/c/90056ece99966182dc0e367f3fd2afab46ada847
- https://git.kernel.org/stable/c/94a0de224ed52eb2ecd4f4cb1b937b674c9fb955
- https://git.kernel.org/stable/c/b58f7ca86a7b8e480c06e30c5163c5d2f4e24023
- https://git.kernel.org/stable/c/bca0902e61731a75fc4860c8720168d9f1bae3b6