CVE-2024-40910ax25: Fix refcount imbalance on inbound connections
- 8.8HighCVSS base score
- 0.45%Exploitation in 30 daysEPSS · top 61% 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 imbalance on inbound connections When releasing a socket in ax25_release(), we call netdev_put() to decrease the refcount on the associated ax.25 device. However, the execution path for accepting an incoming connection never calls netdev_hold(). This imbalance leads to refcount errors, and ultimately to kernel crashes. A typical call trace for the above situation will start with one of the following errors: refcount_t: decrement hit 0; leaking memory. refcount_t: underflow; use-after-free. And will then have a trace like: Call Trace: <TASK> ? show_regs+0x64/0x70 ? __warn+0x83/0x120 ? refcount_warn_saturate+0xb2/0x100 ? report_bug+0x158/0x190 ? prb_read_valid+0x20/0x30 ? handle_bug+0x3e/0x70 ? exc_invalid_op+0x1c/0x70 ? asm_exc_invalid_op+0x1f/0x30 ? refcount_warn_saturate+0xb2/0x100 ? refcount_warn_saturate+0xb2/0x100 ax25_release+0x2ad/0x360 __sock_release+0x35/0xa0 sock_close+0x19/0x20 [...] On reboot (or any attempt to remove the interface), the kernel gets stuck in an infinite loop: unregister_netdevice: waiting for ax0 to become free. Usage count = 0 This patch corrects these issues by ensuring that we call netdev_hold() and ax25_dev_hold() for new connections in ax25_accept(). This makes the logic leading to ax25_accept() match the logic for ax25_bind(): in both cases we increment the refcount, which is ultimately decremented in ax25_release().
Timeline
ID reserved
By Linux
Published
- 2 years later
· 2 years 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 | High8.8 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/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)
- 0.45% · top 61% of all CVEs (14 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 8.8.
Affected products
- affected 9fd75b66b8f68498454d685dc4ba13192ae069b0 – < f4df9d6c8d4e4c818252b0419c2165d66eabd4eb
- affected 9fd75b66b8f68498454d685dc4ba13192ae069b0 – < 52100fd74ad07b53a4666feafff1cd11436362d3
- affected 9fd75b66b8f68498454d685dc4ba13192ae069b0 – < a723a6c8d4831cc8e2c7b0c9f3f0c010d4671964
- affected 9fd75b66b8f68498454d685dc4ba13192ae069b0 – < 3c34fb0bd4a4237592c5ecb5b2e2531900c55774
- 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 6.1.95 – ≤ 6.1.*
- unaffected 6.6.35 – ≤ 6.6.*
- unaffected 6.9.6 – ≤ 6.9.*
- unaffected 6.10 – ≤ *
References
References5
- https://git.kernel.org/stable/c/f4df9d6c8d4e4c818252b0419c2165d66eabd4eb (opens in a new tab)x_transferred
- https://git.kernel.org/stable/c/52100fd74ad07b53a4666feafff1cd11436362d3 (opens in a new tab)x_transferred
- https://git.kernel.org/stable/c/a723a6c8d4831cc8e2c7b0c9f3f0c010d4671964 (opens in a new tab)x_transferred
- https://git.kernel.org/stable/c/3c34fb0bd4a4237592c5ecb5b2e2531900c55774 (opens in a new tab)x_transferred
- https://lists.debian.org/debian-lts-announce/2025/01/msg00001.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-2024-38721 (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-2024-40910)Record last updated .