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CVE-2025-21792— ax25: Fix refcount leak caused by setting SO_BINDTODEVICE sockopt

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于设置SO_BINDTODEVICE选项时未正确增加引用计数，导致引用计数泄漏。

CVSS 7.8 · High EPSS 0.24% · P14

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 24

VendorProduct Version RangeStatus
Linux Linux 9fd75b66b8f68498454d685dc4ba13192ae069b0< 90056ece99966182dc0e367f3fd2afab46ada847 affected
9fd75b66b8f68498454d685dc4ba13192ae069b0< 94a0de224ed52eb2ecd4f4cb1b937b674c9fb955 affected
9fd75b66b8f68498454d685dc4ba13192ae069b0< b58f7ca86a7b8e480c06e30c5163c5d2f4e24023 affected
9fd75b66b8f68498454d685dc4ba13192ae069b0< 470bda72fda0fcf54300466d70ce2de62f7835d2 affected
9fd75b66b8f68498454d685dc4ba13192ae069b0< bca0902e61731a75fc4860c8720168d9f1bae3b6 affected
c44a453ffe16eb08acdc6129ac4fa0192dbc0456 affected
de55a1338e6a48ff1e41ea8db1432496fbe2a62b affected
9e1e088a57c23251f1cfe9601bbd90ade2ea73b9 affected
… +16 more rows
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I. Basic Information for CVE-2025-21792

Vulnerability Information
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Vulnerability Title
ax25: Fix refcount leak caused by setting SO_BINDTODEVICE sockopt
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于设置SO_BINDTODEVICE选项时未正确增加引用计数，导致引用计数泄漏。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 9fd75b66b8f68498454d685dc4ba13192ae069b0 ~ 90056ece99966182dc0e367f3fd2afab46ada847 -
Linux Linux 5.18 -

II. Public POCs for CVE-2025-21792

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III. Intelligence Information for CVE-2025-21792

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Patches & Fixes for CVE-2025-21792 (5)

Same Patch Batch · Linux · 2025-02-27 · 177 CVEs total

CVE-2025-21805 9.8 CRITICAL RDMA/rtrs: Add missing deinit() call
CVE-2025-21796 9.8 CRITICAL nfsd: clear acl_access/acl_default after releasing them
CVE-2025-21707 9.8 CRITICAL mptcp: consolidate suboption status
CVE-2025-21748 9.8 CRITICAL ksmbd: fix integer overflows on 32 bit systems
CVE-2024-58006 9.6 CRITICAL PCI: dwc: ep: Prevent changing BAR size/flags in pci_epc_set_bar()
CVE-2024-57999 8.8 HIGH powerpc/pseries/iommu: IOMMU incorrectly marks MMIO range in DDW
CVE-2025-21735 8.8 HIGH NFC: nci: Add bounds checking in nci_hci_create_pipe()
CVE-2024-57997 8.8 HIGH wifi: wcn36xx: fix channel survey memory allocation size
CVE-2024-57995 8.8 HIGH wifi: ath12k: fix read pointer after free in ath12k_mac_assign_vif_to_vdev()
CVE-2025-21710 8.2 HIGH tcp: correct handling of extreme memory squeeze
CVE-2025-21766 8.1 HIGH ipv4: use RCU protection in __ip_rt_update_pmtu()
CVE-2024-57973 8.1 HIGH rdma/cxgb4: Prevent potential integer overflow on 32bit
CVE-2025-21762 8.1 HIGH arp: use RCU protection in arp_xmit()
CVE-2025-21765 8.1 HIGH ipv6: use RCU protection in ip6_default_advmss()
CVE-2025-21760 8.1 HIGH ndisc: extend RCU protection in ndisc_send_skb()
CVE-2025-21764 7.8 HIGH ndisc: use RCU protection in ndisc_alloc_skb()
CVE-2025-21734 7.8 HIGH misc: fastrpc: Fix copy buffer page size
CVE-2024-58008 7.8 HIGH KEYS: trusted: dcp: fix improper sg use with CONFIG_VMAP_STACK=y
CVE-2024-58010 7.8 HIGH binfmt_flat: Fix integer overflow bug on 32 bit systems
CVE-2025-21791 7.8 HIGH vrf: use RCU protection in l3mdev_l3_out()

Showing top 20 of 177 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-21792

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