Linux: Concurrent Execution using Shared Resource with Improper Synchronization
CVE-2026-64375 is a high-severity concurrent execution using shared resource with improper synchronization vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 6253dfee5afba536bb54fc6fe6c091c3758fafe1, 65bf0d2b6e914f1448d6a2fde193dcf60936a651, de497d7aa2fae453a7e7c8f7d3e8682e565e3aaf 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 0.13% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 6253dfee5afba536bb54fc6fe6c091c3758fafe1 or 65bf0d2b6e914f1448d6a2fde193dcf60936a651 or de497d7aa2fae453a7e7c8f7d3e8682e565e3aaf or 138c692d2b2d63d26f2eb957d0e4fcc5d61f9ff2, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.261 or 5.15.212 or 6.1.178 or 6.6.145, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 778c1144771f0064b6f51bee865cceb0d996f2f9 up to, but not including, 6253dfee5afba536bb54fc6fe6c091c3758fafe1; 778c1144771f0064b6f51bee865cceb0d996f2f9 up to, but not including, 65bf0d2b6e914f1448d6a2fde193dcf60936a651; 778c1144771f0064b6f51bee865cceb0d996f2f9 up to, but not including, de497d7aa2fae453a7e7c8f7d3e8682e565e3aaf; 778c1144771f0064b6f51bee865cceb0d996f2f9 up to, but not including, 138c692d2b2d63d26f2eb957d0e4fcc5d61f9ff2; 778c1144771f0064b6f51bee865cceb0d996f2f9 up to, but not including, 83b17872e3166c295c599279fc9562ac3840c638; 778c1144771f0064b6f51bee865cceb0d996f2f9 up to, but not including, 497c6bae5167428596575f20af6613ff5671f383; 778c1144771f0064b6f51bee865cceb0d996f2f9 up to, but not including, dfd1894cb64cbd8758b461ed713800fe73db4f82; 778c1144771f0064b6f51bee865cceb0d996f2f9 up to, but not including, 6255da28d4bb5349fe18e84cb043ccd394eba75d; and 1 more ranges | 6253dfee5afba536bb54fc6fe6c091c3758fafe1, 65bf0d2b6e914f1448d6a2fde193dcf60936a651, de497d7aa2fae453a7e7c8f7d3e8682e565e3aaf, 138c692d2b2d63d26f2eb957d0e4fcc5d61f9ff2, 83b17872e3166c295c599279fc9562ac3840c638, 497c6bae5167428596575f20af6613ff5671f383 |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Linux | Linux Kernel | 2.6.18 up to, but not including, 5.10.261; 5.11 up to, but not including, 5.15.212; 5.16 up to, but not including, 6.1.178; 6.2 up to, but not including, 6.6.145; 6.7 up to, but not including, 6.12.97; 6.13 up to, but not including, 6.18.40; 6.19 up to, but not including, 7.1.4 | 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40 |
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
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- 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:L/AC:L/PR:L/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: proc: protect ptrace_may_access() with exec_update_lock (FD links) proc_pid_get_link() and proc_pid_readlink() currently look up the task from the pid once, then do the ptrace access check on that task, then look up the task from the pid a second time to do the actual access. That's racy in several ways. To fix it, pass the task to the ->proc_get_link() handler, and instead of proc_fd_access_allowed(), introduce a new helper call_proc_get_link() that looks up and locks the task, does the access check, and calls ->proc_get_link().
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Concurrent Execution using Shared Resource with Improper Synchronization
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
How developers prevent this class of flaw
- In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.
- Use thread-safe capabilities such as the data access abstraction in Spring.
- Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring. Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/138c692d2b2d63d26f2eb957d0e4fcc5d61f9ff2
- git.kernel.org/stable/c/497c6bae5167428596575f20af6613ff5671f383
- git.kernel.org/stable/c/6253dfee5afba536bb54fc6fe6c091c3758fafe1
- git.kernel.org/stable/c/6255da28d4bb5349fe18e84cb043ccd394eba75d
- git.kernel.org/stable/c/65bf0d2b6e914f1448d6a2fde193dcf60936a651
- git.kernel.org/stable/c/83b17872e3166c295c599279fc9562ac3840c638
- git.kernel.org/stable/c/de497d7aa2fae453a7e7c8f7d3e8682e565e3aaf
- git.kernel.org/stable/c/dfd1894cb64cbd8758b461ed713800fe73db4f82
Third-party and government advisories
- cert-portal.siemens.com/productcert/html/ssa-019113.htmlThird Party Advisory
Other references
Recent Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities
- 7.0 High severity
- 7.1 High severity
- 8.2 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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