Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
Linux Linux — ax25: Fix refcount imbalance on inbound connections
AV AC PR UI S C I A CVSS EPSS %ile KEV
L L L N U N N H 5.5 .0045 37.3 —
AFFECTED
Product Versions Fixed
Linux 9fd75b66b8f68498454d685dc4ba13192ae069b0 – —
Linux 5.18 – 6.1.95
TIMELINE
Jul 12 Reserved by Linux
Jul 12 Published (CNA: Linux)
Aug 4 RESCORED — CVE-2024-40910 (Linux). CVSS 8.8 → 5.5 (NVD).
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().
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
| July 12, 2024 | Reserved | Reserved by Linux |
| July 12, 2024 | Published | Published (CNA: Linux) |
| August 4, 2026 | RESCORED | RESCORED — CVE-2024-40910 (Linux). CVSS 8.8 → 5.5 (NVD). |
Affected
Affected products and packages — 2 rows
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
| Linux | Linux | — | 9fd75b66b8f68498454d685dc4ba13192ae069b0 | — |
| Linux | Linux | — | 5.18 | 6.1.95 |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2024-40910 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.