CVE-2026-64422: net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes

mediumCVSS 5.5CVE-2026-64422

CSIRTS triage

vendor: Linux product: KernelOther

What: There is a vulnerability related to TCP reordering sysctl writes and MTU probe sizes.
Who is affected: Deployments of the Linux kernel that utilize TCP settings.
Urgency: Remediation is important to ensure network stability, with no known exploits currently.
Action: Update to the latest kernel version that includes the fix.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 5.5
Published: 2026-07-14
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64422

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-644220.13% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 3% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-64422	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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highCVE-2026-64422: In the Linux kernel, the following vulnerability has been resolved: net: ipv4: bound TCP reord…nvd

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