Linux: Improper Locking
CVE-2026-64534 is a critical-severity improper locking vulnerability in Linux, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 22ec7a9fe9153d2737ee9b2fa6d2e43a1491decf, ba35b1c674ca3841c0dfadd698f2c1b3ec542d4e, c7874dad84b20433c0fe3919f291a762d40de08b as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.32% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to 22ec7a9fe9153d2737ee9b2fa6d2e43a1491decf or ba35b1c674ca3841c0dfadd698f2c1b3ec542d4e or c7874dad84b20433c0fe3919f291a762d40de08b or e602c93b25bda4a9d0ff1791a4bdbfdcbb074af1, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 91edfca6f8b364d60cde3ddefaf7d03ddf35774b up to, but not including, 22ec7a9fe9153d2737ee9b2fa6d2e43a1491decf; fda871c0ba5d2eed2cd1c881573168129da70058 up to, but not including, ba35b1c674ca3841c0dfadd698f2c1b3ec542d4e; fda871c0ba5d2eed2cd1c881573168129da70058 up to, but not including, c7874dad84b20433c0fe3919f291a762d40de08b; fda871c0ba5d2eed2cd1c881573168129da70058 up to, but not including, e602c93b25bda4a9d0ff1791a4bdbfdcbb074af1; fda871c0ba5d2eed2cd1c881573168129da70058 up to, but not including, d306da8833e75f669d93424fd84940236f3850bc; fda871c0ba5d2eed2cd1c881573168129da70058 up to, but not including, 2ed3c9d955e8cd6361f130623baa664a75fb345f; fda871c0ba5d2eed2cd1c881573168129da70058 up to, but not including, 4606467a75cfc16721937272ed29462a750b60c8; 4b17476d809273617d3317fa0d4ae78aa488d760; and 3 more ranges | 22ec7a9fe9153d2737ee9b2fa6d2e43a1491decf, ba35b1c674ca3841c0dfadd698f2c1b3ec542d4e, c7874dad84b20433c0fe3919f291a762d40de08b, e602c93b25bda4a9d0ff1791a4bdbfdcbb074af1, d306da8833e75f669d93424fd84940236f3850bc, 2ed3c9d955e8cd6361f130623baa664a75fb345f |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: check INIT_FAILED before nvmet_req_uninit in digest error path In nvmet_tcp_try_recv_ddgst(), when a data digest mismatch is detected, nvmet_req_uninit() is called unconditionally. However, if the command arrived via the nvmet_tcp_handle_req_failure() path, nvmet_req_init() had returned false and percpu_ref_tryget_live() was never executed. The unconditional percpu_ref_put() inside nvmet_req_uninit() then causes a refcount underflow, leading to a WARNING in percpu_ref_switch_to_atomic_rcu, a use-after-free diagnostic, and eventually a permanent workqueue deadlock. Check cmd->flags & NVMET_TCP_F_INIT_FAILED before calling nvmet_req_uninit(), matching the existing pattern in nvmet_tcp_execute_request().
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Locking
The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.
How developers prevent this class of flaw
- Use industry standard APIs to implement locking mechanism.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
- git.kernel.org/stable/c/22ec7a9fe9153d2737ee9b2fa6d2e43a1491decf
- git.kernel.org/stable/c/2ed3c9d955e8cd6361f130623baa664a75fb345f
- git.kernel.org/stable/c/4606467a75cfc16721937272ed29462a750b60c8
- git.kernel.org/stable/c/ba35b1c674ca3841c0dfadd698f2c1b3ec542d4e
- git.kernel.org/stable/c/c7874dad84b20433c0fe3919f291a762d40de08b
- git.kernel.org/stable/c/d306da8833e75f669d93424fd84940236f3850bc
- git.kernel.org/stable/c/e602c93b25bda4a9d0ff1791a4bdbfdcbb074af1
Recent Improper Locking vulnerabilities
- 7.5 High severity
- 9.8 Critical severity
- 7.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.8 High severity
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