CVE-2023-0386
CVE-2023-0386 is a security flaw in Linux Kernel, the core of Linux, which runs most servers, Android phones and many home routers. Attackers are using a flaw in Linux Kernel. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 17 Jun 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. Linux has published a fix or advice.
Description
CISA calls it an improper ownership management in Linux Kernel. In its words: “Linux Kernel contains an improper ownership management vulnerability, where unauthorized access to the execution of the setuid file with capabilities was found in the Linux kernel’s OverlayFS subsystem in how a user copies a capable file from a nosuid mount into another mount. This uid mapping bug allows a local user to escalate their privileges on the system.”[1]
The underlying weakness is CWE-282, in MITRE’s list of common software weaknesses.[2]
It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Linux’s advisory has them[3]. CISA names the product as Linux Kernel.
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 17 Jun 2025, 818 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 8 Jul 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 8%. That’s in the top 6% 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, or not in use. CISA gave US government agencies until 8 Jul 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 8%.[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 ·
Every Linux flaw on CISA’s list · Everything added in June 2025
References
- ^ Cybersecurity and Infrastructure Security Agency. “Linux Kernel Improper Ownership Management Vulnerability”. Known Exploited Vulnerabilities Catalog, added 17 Jun 2025.
- ^ National Institute of Standards and Technology. “CVE-2023-0386 Detail”. National Vulnerability Database, published 22 Mar 2023.
- ^ Linux. Advisories and fixes: git.kernel.org, access.redhat.com, security.netapp.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.079, percentile 94.7, 31 Oct 2026.
- CVE Program. “CVE-2023-0386”. 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.