CVE-2025-21792ax25: Fix refcount leak caused by setting SO_BINDTODEVICE sockopt
- 7.8HighCVSS base score
- 0.24%Exploitation in 30 daysEPSS · top 85% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By Linux
- 2 months later
· 2 months later
Published
- 17 months later
· 17 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| CISA-ADPADP (enrichment) | 3.1 | Medium5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Modified | 3.1 | Medium5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.24% · top 85% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Affected products
- affected 9fd75b66b8f68498454d685dc4ba13192ae069b0 – < 90056ece99966182dc0e367f3fd2afab46ada847
- affected 9fd75b66b8f68498454d685dc4ba13192ae069b0 – < 94a0de224ed52eb2ecd4f4cb1b937b674c9fb955
- affected 9fd75b66b8f68498454d685dc4ba13192ae069b0 – < b58f7ca86a7b8e480c06e30c5163c5d2f4e24023
- affected 9fd75b66b8f68498454d685dc4ba13192ae069b0 – < 470bda72fda0fcf54300466d70ce2de62f7835d2
- affected 9fd75b66b8f68498454d685dc4ba13192ae069b0 – < bca0902e61731a75fc4860c8720168d9f1bae3b6
- affected c44a453ffe16eb08acdc6129ac4fa0192dbc0456
- affected de55a1338e6a48ff1e41ea8db1432496fbe2a62b
- affected 9e1e088a57c23251f1cfe9601bbd90ade2ea73b9
- affected b20a5ab0f5fb175750c6bafd4cf12daccf00c738
- affected 452ae92b99062d2f6a34324eaf705a3b7eac9f8b
- affected 534156dd4ed768e30a43de0036f45dca7c54818f
- affected 4.14.277 – < 4.15
- affected 4.19.240 – < 4.20
- affected 5.4.190 – < 5.5
- affected 5.10.112 – < 5.11
- affected 5.15.35 – < 5.16
- affected 5.17.2 – < 5.18
- affected 5.18
- unaffected < 5.18
- unaffected 6.1.129 – ≤ 6.1.*
- unaffected 6.6.79 – ≤ 6.6.*
- unaffected 6.12.16 – ≤ 6.12.*
- unaffected 6.13.4 – ≤ 6.13.*
- unaffected 6.14 – ≤ *
References
References6
- https://git.kernel.org/stable/c/90056ece99966182dc0e367f3fd2afab46ada847 (opens in a new tab)
- https://git.kernel.org/stable/c/94a0de224ed52eb2ecd4f4cb1b937b674c9fb955 (opens in a new tab)
- https://git.kernel.org/stable/c/b58f7ca86a7b8e480c06e30c5163c5d2f4e24023 (opens in a new tab)
- https://git.kernel.org/stable/c/470bda72fda0fcf54300466d70ce2de62f7835d2 (opens in a new tab)
- https://git.kernel.org/stable/c/bca0902e61731a75fc4860c8720168d9f1bae3b6 (opens in a new tab)
- https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2025-5128 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2025-21792)Record last updated .