Linux: Concurrent Execution using Shared Resource with Improper Synchronization
CVE-2026-53050 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 2bdc80f4619411e5bd4a3ef23f51e14021ed457c, f9438cb8c8ec3adc84b2b450a3aab0123d074c3b, ac8a2e0d287ebf35e5d7e51e260b4e146648ba4a 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 0.1% 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 2bdc80f4619411e5bd4a3ef23f51e14021ed457c or f9438cb8c8ec3adc84b2b450a3aab0123d074c3b or ac8a2e0d287ebf35e5d7e51e260b4e146648ba4a or 6678dde265708003c2b42551af4a2e3cb05decd5, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.20 or 5.5 or 5.10.258 or 5.15.209, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 22c06bf1f99ec3ec16b1a81342becba4c59a1f16 up to, but not including, 2bdc80f4619411e5bd4a3ef23f51e14021ed457c; 56e96b38d2f7cd95b3c30eb70decac7233915e0a up to, but not including, f9438cb8c8ec3adc84b2b450a3aab0123d074c3b; 12a820a9923c11e8e898da9f82c8aded70cdcd16 up to, but not including, ac8a2e0d287ebf35e5d7e51e260b4e146648ba4a; 869b6ea1609f655a43251bf41757aa44e5350a8f up to, but not including, 6678dde265708003c2b42551af4a2e3cb05decd5; 869b6ea1609f655a43251bf41757aa44e5350a8f up to, but not including, 61e25f664dc2a08299e07d84c85776abc2350f75; 869b6ea1609f655a43251bf41757aa44e5350a8f up to, but not including, fdd424d7c35633ac577fd87d1b043d1b8a6cd350; 869b6ea1609f655a43251bf41757aa44e5350a8f up to, but not including, 82cbdb4c1ebb5ea7d7bd45c18d3483b5bd32ebc1; 869b6ea1609f655a43251bf41757aa44e5350a8f up to, but not including, e93ab401da4b2e2c1b8ef2424de2f238d51c8b2d; and 10 more ranges | 2bdc80f4619411e5bd4a3ef23f51e14021ed457c, f9438cb8c8ec3adc84b2b450a3aab0123d074c3b, ac8a2e0d287ebf35e5d7e51e260b4e146648ba4a, 6678dde265708003c2b42551af4a2e3cb05decd5, 61e25f664dc2a08299e07d84c85776abc2350f75, fdd424d7c35633ac577fd87d1b043d1b8a6cd350 |
| 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 | 4.19.297 up to, but not including, 4.20; 5.4.259 up to, but not including, 5.5; 5.10.199 up to, but not including, 5.10.258; 5.15.136 up to, but not including, 5.15.209; 6.1.59 up to, but not including, 6.1.175; 6.5.8 up to, but not including, 6.6; 6.6.1 up to, but not including, 6.6.141; 6.7 up to, but not including, 6.12.91; and 3 more ranges | 4.20, 5.5, 5.10.258, 5.15.209, 6.1.175, 6.6 |
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: quota: Fix race of dquot_scan_active() with quota deactivation dquot_scan_active() can race with quota deactivation in quota_release_workfn() like: CPU0 (quota_release_workfn) CPU1 (dquot_scan_active) ============================== ============================== spin_lock(&dq_list_lock); list_replace_init( &releasing_dquots, &rls_head); /* dquot X on rls_head, dq_count == 0, DQ_ACTIVE_B still set */ spin_unlock(&dq_list_lock); synchronize_srcu(&dquot_srcu); spin_lock(&dq_list_lock); list_for_each_entry(dquot, &inuse_list, dq_inuse) { /* finds dquot X */ dquot_active(X) -> true atomic_inc(&X->dq_count); } spin_unlock(&dq_list_lock); spin_lock(&dq_list_lock); dquot = list_first_entry(&rls_head); WARN_ON_ONCE(atomic_read(&dquot->dq_count)); The problem is not only a cosmetic one as under memory pressure the caller of dquot_scan_active() can end up working on freed dquot. Fix the problem by making sure the dquot is removed from releasing list when we acquire a reference to it.
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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/2bdc80f4619411e5bd4a3ef23f51e14021ed457c
- git.kernel.org/stable/c/61e25f664dc2a08299e07d84c85776abc2350f75
- git.kernel.org/stable/c/6678dde265708003c2b42551af4a2e3cb05decd5
- git.kernel.org/stable/c/82cbdb4c1ebb5ea7d7bd45c18d3483b5bd32ebc1
- git.kernel.org/stable/c/ac8a2e0d287ebf35e5d7e51e260b4e146648ba4a
- git.kernel.org/stable/c/e93ab401da4b2e2c1b8ef2424de2f238d51c8b2d
- git.kernel.org/stable/c/f9438cb8c8ec3adc84b2b450a3aab0123d074c3b
- git.kernel.org/stable/c/fdd424d7c35633ac577fd87d1b043d1b8a6cd350
Other references
Recent Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities
- 9.8 Critical severity
- 7.5 High severity
- 7.8 High severity
- 7.8 High severity
- 7.1 High severity
- 7.8 High severity
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