Summary
In the Linux kernel, the following vulnerability has been resolved: net: avoid race between...
In the Linux kernel, the following vulnerability has been resolved:
net: avoid race between device unregistration and ethnl ops
The following trace can be seen if a device is being unregistered while
its number of channels are being modified.
DEBUG_LOCKS_WARN_ON(lock->magic != lock)
WARNING: CPU: 3 PID: 3754 at kernel/locking/mutex.c:564 __mutex_lock+0xc8a/0x1120
CPU: 3 UID: 0 PID: 3754 Comm: ethtool Not tainted 6.13.0-rc6+ #771
RIP: 0010:__mutex_lock+0xc8a/0x1120
Call Trace:
ethtool_check_max_channel+0x1ea/0x880
ethnl_set_channels+0x3c3/0xb10
ethnl_default_set_doit+0x306/0x650
genl_family_rcv_msg_doit+0x1e3/0x2c0
genl_rcv_msg+0x432/0x6f0
netlink_rcv_skb+0x13d/0x3b0
genl_rcv+0x28/0x40
netlink_unicast+0x42e/0x720
netlink_sendmsg+0x765/0xc20
__sys_sendto+0x3ac/0x420
__x64_sys_sendto+0xe0/0x1c0
do_syscall_64+0x95/0x180
entry_SYSCALL_64_after_hwframe+0x76/0x7e
This is because unregister_netdevice_many_notify might run before the
rtnl lock section of ethnl operations, eg. set_channels in the above
example. In this example the rss lock would be destroyed by the device
unregistration path before being used again, but in general running
ethnl operations while dismantle has started is not a good idea.
Fix this by denying any operation on devices being unregistered. A check
was already there in ethnl_ops_begin, but not wide enough.
Note that the same issue cannot be seen on the ioctl version
(__dev_ethtool) because the device reference is retrieved from within
the rtnl lock section there. Once dismantle started, the net device is
unlisted and no reference will be found.
Impact
Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing. Typical impact: TOCTOU exploits, data corruption, or privilege escalation.
CVE-2025-21701 has a CVSS score of 7.4 (High). The vector is requires local access, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2025-21701? CVE-2025-21701 is a high-severity race condition vulnerability. No fixed version is listed yet. Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing.
- How severe is CVE-2025-21701? CVE-2025-21701 has a CVSS score of 7.4 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Is there a fix for CVE-2025-21701? No fixed version is listed for CVE-2025-21701 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2025-21701 exploitable, and should I be worried? Whether CVE-2025-21701 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-21701 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.