Linux: Concurrent Execution using Shared Resource with Improper Synchronization
CVE-2025-71221 is a high-severity concurrent execution using shared resource with improper synchronization vulnerability in Linux, with a CVSS 3.1 base score of 7.0 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 3f0e0e2d9e752570041e95fd04635e2580097819, dfb5e05227745de43b7fd589721817a4337c970d, eba0c75670c022cb1f948600db972524bcfe8166 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 0.12% 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 3f0e0e2d9e752570041e95fd04635e2580097819 or dfb5e05227745de43b7fd589721817a4337c970d or eba0c75670c022cb1f948600db972524bcfe8166 or fc023b8fab057f0c910856ff36d3e12a30b7af4a, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.18.10 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 1b38da264674d6a0fe26a63996b8f88b88c3da48 up to, but not including, 3f0e0e2d9e752570041e95fd04635e2580097819; 1b38da264674d6a0fe26a63996b8f88b88c3da48 up to, but not including, dfb5e05227745de43b7fd589721817a4337c970d; 1b38da264674d6a0fe26a63996b8f88b88c3da48 up to, but not including, eba0c75670c022cb1f948600db972524bcfe8166; 1b38da264674d6a0fe26a63996b8f88b88c3da48 up to, but not including, fc023b8fab057f0c910856ff36d3e12a30b7af4a; 1b38da264674d6a0fe26a63996b8f88b88c3da48 up to, but not including, 9f665b3c3d9a168410251f27a5d019b7bf93185c; 1b38da264674d6a0fe26a63996b8f88b88c3da48 up to, but not including, a143545855bc2c6e1330f6f57ae375ac44af00a7; 3.16 | 3f0e0e2d9e752570041e95fd04635e2580097819, dfb5e05227745de43b7fd589721817a4337c970d, eba0c75670c022cb1f948600db972524bcfe8166, fc023b8fab057f0c910856ff36d3e12a30b7af4a, 9f665b3c3d9a168410251f27a5d019b7bf93185c, a143545855bc2c6e1330f6f57ae375ac44af00a7 |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.6 and later; V3.1.5 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; V3.1.5 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; V3.1.5 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; V3.1.5 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; V3.1.5 and later; V3.1.7 and later | Not stated |
| Linux | Linux Kernel | 3.16 up to, but not including, 6.18.10; 6.19 | 6.18.10 |
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
- HighSuccess depends on conditions outside the attacker's control.
- 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:H/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.0 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: dmaengine: mmp_pdma: Fix race condition in mmp_pdma_residue() Add proper locking in mmp_pdma_residue() to prevent use-after-free when accessing descriptor list and descriptor contents. The race occurs when multiple threads call tx_status() while the tasklet on another CPU is freeing completed descriptors: CPU 0 CPU 1 ----- ----- mmp_pdma_tx_status() mmp_pdma_residue() -> NO LOCK held list_for_each_entry(sw, ..) DMA interrupt dma_do_tasklet() -> spin_lock(&desc_lock) list_move(sw->node, ...) spin_unlock(&desc_lock) | dma_pool_free(sw) <- FREED! -> access sw->desc <- UAF! This issue can be reproduced when running dmatest on the same channel with multiple threads (threads_per_chan > 1). Fix by protecting the chain_running list iteration and descriptor access with the chan->desc_lock spinlock.
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
Other references
- git.kernel.org/stable/c/3f0e0e2d9e752570041e95fd04635e2580097819
- git.kernel.org/stable/c/dfb5e05227745de43b7fd589721817a4337c970d
- git.kernel.org/stable/c/eba0c75670c022cb1f948600db972524bcfe8166
- git.kernel.org/stable/c/fc023b8fab057f0c910856ff36d3e12a30b7af4a
- cert-portal.siemens.com/productcert/html/ssa-019113.html
- cert-portal.siemens.com/productcert/html/ssa-082556.html
- cert-portal.siemens.com/productcert/html/ssa-457936.html
Recent Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities
- 9.0 Critical severity
- 7.0 High severity
- 7.5 High severity
- 7.0 High severity
- 7.0 High severity
- 7.8 High severity
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