Exploited vulnerability · CISA KEV
Yes. CVE-2026-46300, Linux Kernel Missing Initialization of a Variable Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 28 Oct 2026, 158 days after it was published. It affects Linux Kernel. If you run it, CISA's required action is: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
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.
| Vendor | Linux (32 exploited CVEs in KEV) |
| Product | Kernel |
| Vulnerability | Linux Kernel Missing Initialization of a Variable Vulnerability |
| Weakness | CWE-456 |
| Published | 23 May 2026 |
| Added to KEV | 28 Oct 2026 |
| Reported by (CNA) | Linux |
Yes. CISA added CVE-2026-46300 to the Known Exploited Vulnerabilities catalog on 28 Oct 2026, which means there is reliable evidence of exploitation in the wild.
CISA does not list known ransomware use for it. That can change, and exploitation alone is reason to fix it first.
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. Check Linux's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected Kernel and watch it for signs of compromise.
Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in October 2026 · Linux scorecard · act-now radar.
We check exposure across your estate, patch or mitigate with your team, and set up detection for what attackers do after exploiting it.
Get in touch →