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CVE-2026-46300

Linux Kernel•HIGH · CVSS 7.8• In the wild In CISA KEV

What is CVE-2026-46300?

In the Linux kernel, the following vulnerability has been resolved: net: skbuff: preserve shared-frag marker during coalescing skb_try_coalesce() can attach paged frags from @from to @to. If @from has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same externally-owned or page-cache-backed frags, but the shared-frag marker is currently lost. That breaks the invariant relied on by later in-place writers. In particular, ESP input checks skb_has_shared_frag() before deciding whether an uncloned nonlinear skb can skip skb_cow_data(). If TCP receive coalescing has moved shared frags into an unmarked skb, ESP can see skb_has_shared_frag() as false and decrypt in place over page-cache backed frags. Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged frags. The tailroom copy path does not need the marker because it copies bytes into @to's linear data rather than transferring frag descriptors.

CVSS7.8 NVD 3.1

SeverityHIGH

Exploitation In the wild In CISA KEV

EPSS10% · P96

Triage statusActive Exploit

ActionPatch immediately

CVSS vectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWECWE-787, CWE-456, CWE-123

NVD published2026-05-23

NVD last modified2026-10-29

Timeline

2026-05-23Published to the U.S. National Vulnerability Database (NVD)
2026-10-28Added to the CISA Known Exploited Vulnerabilities (KEV) catalog
2026-10-29First covered in a defend.network daily briefing
2026-10-29NVD record last updated
2026-10-31CISA federal remediation deadline (BOD 22-01)

CISA Known Exploited Vulnerability

Linux Kernel Missing Initialization of a Variable Vulnerability

Added to KEV2026-10-28

Federal patch deadline2026-10-31

Known ransomware useUnknown

Affected product

Linux Kernel

Remediation Steps

Apply the vendor security update for Linux Kernel as a priority.
Restrict network exposure of the affected service to trusted sources until patched.
Review logs and detections for indicators of exploitation.
Confirm fixed versions against the official vendor advisory before deploying.

References

Referenced in our briefings & reports

Vulnerability Priority Report – Week 4 of October 2026 (October 26 – November 1)
Volt Typhoon dismantled; PHP RCE active; Microsoft patches 1,400+ flaws (2026-10-29)

Related vulnerabilities

CVE-2026-53362 – Linux Kernel (same product)
CVE-2026-53266 – Linux Kernel (same product)
CVE-2025-39964 – Linux Kernel (same product)
CVE-2025-39682 – Linux Kernel (same product)
CVE-2026-46331 – Linux Kernel (same product)
CVE-2022-0995 – Linux Kernel (same product)

Linux: 31 known exploited vulnerabilities (CISA KEV) →

Browse all tracked CVEs in the defend.network CVE database →

🤖 This CVE page is generated by defend.network from NVD, CISA KEV, EPSS, and our verified daily briefings. Severity and exploitation data come from official sources; always verify remediation steps against the official vendor advisory before acting in production.