Linux: Concurrent Execution using Shared Resource with Improper Synchronization
CVE-2025-21718 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 52f5aff33ca73b2c2fa93f40a3de308012e63cf4, 0d5bca3be27bfcf8f980f2fed49b6cbb7dafe4a1, 1409b45d4690308c502c6caf22f01c3c205b4717 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 0.17% 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 52f5aff33ca73b2c2fa93f40a3de308012e63cf4 or 0d5bca3be27bfcf8f980f2fed49b6cbb7dafe4a1 or 1409b45d4690308c502c6caf22f01c3c205b4717 or f55c88e3ca5939a6a8a329024aed8f3d98eea8e4, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.129 or 6.6.76 or 6.12.13 or 6.13.2, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 52f5aff33ca73b2c2fa93f40a3de308012e63cf4; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 0d5bca3be27bfcf8f980f2fed49b6cbb7dafe4a1; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 1409b45d4690308c502c6caf22f01c3c205b4717; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, f55c88e3ca5939a6a8a329024aed8f3d98eea8e4; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 51c128ba038cf1b79d605cbee325919b45ab95a5; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 1992fb261c90e9827cf5dc3115d89bb0853252c9; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 58051a284ac18a3bb815aac6289a679903ddcc3f; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 5de7665e0a0746b5ad7943554b34db8f8614a196; and 1 more ranges | 52f5aff33ca73b2c2fa93f40a3de308012e63cf4, 0d5bca3be27bfcf8f980f2fed49b6cbb7dafe4a1, 1409b45d4690308c502c6caf22f01c3c205b4717, f55c88e3ca5939a6a8a329024aed8f3d98eea8e4, 51c128ba038cf1b79d605cbee325919b45ab95a5, 1992fb261c90e9827cf5dc3115d89bb0853252c9 |
| 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 | 2.6.12 up to, but not including, 6.1.129; 6.2 up to, but not including, 6.6.76; 6.7 up to, but not including, 6.12.13; 6.13 up to, but not including, 6.13.2 | 6.1.129, 6.6.76, 6.12.13, 6.13.2 |
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: net: rose: fix timer races against user threads Rose timers only acquire the socket spinlock, without checking if the socket is owned by one user thread. Add a check and rearm the timers if needed. BUG: KASAN: slab-use-after-free in rose_timer_expiry+0x31d/0x360 net/rose/rose_timer.c:174 Read of size 2 at addr ffff88802f09b82a by task swapper/0/0 CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.13.0-rc5-syzkaller-00172-gd1bf27c4e176 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x169/0x550 mm/kasan/report.c:489 kasan_report+0x143/0x180 mm/kasan/report.c:602 rose_timer_expiry+0x31d/0x360 net/rose/rose_timer.c:174 call_timer_fn+0x187/0x650 kernel/time/timer.c:1793 expire_timers kernel/time/timer.c:1844 [inline] __run_timers kernel/time/timer.c:2418 [inline] __run_timer_base+0x66a/0x8e0 kernel/time/timer.c:2430 run_timer_base kernel/time/timer.c:2439 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2449 handle_softirqs+0x2d4/0x9b0 kernel/softirq.c:561 __do_softirq kernel/softirq.c:595 [inline] invoke_softirq kernel/softirq.c:435 [inline] __irq_exit_rcu+0xf7/0x220 kernel/softirq.c:662 irq_exit_rcu+0x9/0x30 kernel/softirq.c:678 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1049 </IRQ>
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/1992fb261c90e9827cf5dc3115d89bb0853252c9
- git.kernel.org/stable/c/51c128ba038cf1b79d605cbee325919b45ab95a5
- git.kernel.org/stable/c/58051a284ac18a3bb815aac6289a679903ddcc3f
- git.kernel.org/stable/c/5de7665e0a0746b5ad7943554b34db8f8614a196
- git.kernel.org/stable/c/f55c88e3ca5939a6a8a329024aed8f3d98eea8e4
Other references
- git.kernel.org/stable/c/0d5bca3be27bfcf8f980f2fed49b6cbb7dafe4a1
- git.kernel.org/stable/c/1409b45d4690308c502c6caf22f01c3c205b4717
- git.kernel.org/stable/c/52f5aff33ca73b2c2fa93f40a3de308012e63cf4
- lists.debian.org/debian-lts-announce/2025/03/msg00028.html
- lists.debian.org/debian-lts-announce/2025/05/msg00030.html
- cert-portal.siemens.com/productcert/html/ssa-019113.html
- cert-portal.siemens.com/productcert/html/ssa-457936.html
Recent Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities
- 7.2 High severity
- 7.5 High severity
- 8.4 High severity
- 7.0 High severity
- 7.0 High severity
- 7.0 High severity
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