CVE-2025-38352
CVE-2025-38352 is a security flaw in Linux Kernel, the core of Linux, which runs most servers, Android phones and many home routers. Attackers can corrupt memory in Linux Kernel, which they use to take it over. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 4 Sep 2025.[1]
Linux Kernel is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Fixed by 8 commits to Linux, in the releases that include them.
Description
CISA calls it a time-of-check time-of-use (TOCTOU) race condition in Linux Kernel. In its words: “Linux kernel contains a time-of-check time-of-use (TOCTOU) race condition vulnerability that has a high impact on confidentiality, integrity, and availability.”[1]
The CVE record adds: “In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del() If an exiting non-autoreaping task has already passed exit_notify() and calls handle_posix_cpu_timers() from IRQ, it can be reaped by its parent or debugger right after unlock_task_sighand(). If a concurrent posix_cpu_timer_del() runs at that moment, it won't be able to detect timer->it.cpu.firing != 0: cpu_timer_task_rcu() and/or lock_task_sighand() will fail. Add the tsk->exit_state check into run_posix_cpu_timers() to fix this. This fix is not needed if CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y, because exit_task_work() is called before exit_notify(). But the check still makes sense, task_work_add(&tsk->posix_cputimers_work.work) will fail anyway in this case.”[2]
The underlying weakness is CWE-367, in MITRE’s list of common software weaknesses.
It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| Linux | commit 78a4b8e3795b |
| Linux | commit c076635b3a42 |
| Linux | commit 2f3daa04a932 |
| Linux | commit 764a7a5dfda2 |
| Linux | commit 2c72fe18cc5f |
| Linux | commit c29d5318708e |
| Linux | commit 460188bc042a |
| Linux | commit f90fff1e152d |
Most families won’t have Linux Kernel; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 4 Sep 2025, 44 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 25 Sep 2025 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 1%. That’s in the top 29% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Linux has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]
- Check whether you use it.Linux Kernel is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed (fixed by 8 commits to Linux, in the releases that include them), or not in use. CISA gave US government agencies until 25 Sep 2025 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 7.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 1%.[4] |
See also
Other Linux Kernel flaws
- CVE-2026-46300: missing initialization of a variable ·
- CVE-2026-53266: out-of-bounds write ·
- CVE-2025-39964: race condition ·
- CVE-2025-39682: improper check for unusual or exceptional conditions ·
- CVE-2026-53362: unspecified ·
- CVE-2022-0995: out-of-bounds write ·
Similar flaws
- CVE-2025-22224, VMware ESXi and Workstation: TOCTOU race condition ·
- CVE-2024-30088, Microsoft Windows: kernel TOCTOU race condition ·
- CVE-2022-48618, Apple devices: memory corruption ·
- CVE-2023-35311, Microsoft Outlook: security feature bypass ·
Added the same day
- CVE-2025-53690, Sitecore products: deserialization of untrusted data ·
- CVE-2025-48543, Android Runtime: use-after-free ·
Every Linux flaw on CISA’s list · Everything added in September 2025
References
- ^ Cybersecurity and Infrastructure Security Agency. “Linux Kernel Time-of-Check Time-of-Use (TOCTOU) Race Condition Vulnerability”. Known Exploited Vulnerabilities Catalog, added 4 Sep 2025.
- ^ National Institute of Standards and Technology. “CVE-2025-38352 Detail”. National Vulnerability Database, published 22 Jul 2025.
- ^ Linux. Advisories and fixes: git.kernel.org, source.android.com, git.kernel.org, git.kernel.org, git.kernel.org, and 3 more on NVD’s record.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.014, percentile 71.7, 31 Oct 2026.
- CVE Program. “CVE-2025-38352”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.