CVE-2026-46300 Linux Kernel: software flaw
In plain words: A mistake in the software that attackers have found a way to abuse. Depends on the product — see the description and the vendor advisory.
Confirmed exploited by CISA on · US federal patch deadline Oct 31, 2026
What to do
- Install Linux's security update for Kernel. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Turn on automatic updates for the operating system and for Office, PDF and archive apps.
- Be careful with unexpected attachments — documents, .zip/.rar files and shortcuts are common bait.
- Use a normal (non-admin) account day to day and keep built-in protection like Microsoft Defender on.
Who is affected
Could reach you. This one is aimed at devices or apps of the kind people own.
What's at risk: Your files, saved passwords and accounts. Many of these let a program that is already running gain full administrator control.
The details
- Official name
- Linux Kernel Missing Initialization of a Variable Vulnerability
- Product
- Linux Kernel
- CISA description
- Linux Kernel contains a missing initialization of a variable vulnerability that could allow for unintended modification of page-cache-backed data via failure to preserve the shared-fragment marker during socket buffer coalescing, causing ESP input processing to decrypt shared fragments in place. This vulnerability can be chained with CVE-2026-109618 and CVE-2026-109619 to implant PHP webshells and run commands as root.
- Type of flaw
- Software flaw (CWE-456)
- Confirmed exploited
- Oct 28, 2026
- US federal patch deadline
- Oct 31, 2026
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Answering about CVE-2026-46300 ·
Questions about CVE-2026-46300
Is CVE-2026-46300 being exploited?
Yes. CISA added CVE-2026-46300 to its Known Exploited Vulnerabilities catalog on Oct 28, 2026, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2026-46300?
Install Linux's security update for Kernel. If no update exists, follow the vendor's workaround or stop using the product until one ships. Turn on automatic updates for the operating system and for Office, PDF and archive apps.
Am I affected by CVE-2026-46300?
Only if you use Linux Kernel. This one is aimed at devices or apps of the kind people own.