CVE-2026-63828: apparmor: mediate the implicit connect of TCP fast open sendmsg

CSIRTS triage

What

The implicit connect of TCP fast open sendmsg is not properly mediated.

Who is affected

Deployments using apparmor may be affected.

Urgency

Remediation is necessary to prevent potential issues, though exploitation is not currently reported.

Action

Apply the patch for CVE-2026-63828.

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

Details

Source

Microsoft Security Response Center (INTL · vendor-psirt · site)

Severity

critical — CVSS 9.8

Published

2026-07-14

Exploitation

Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-63828

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-2026-638280.13% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 3% of all scored CVEs.

Referenced CVEs

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

• unknownMultiples vulnérabilités dans le noyau Linux de Debian LTS (31 juillet 2026)cert-fr-avis
• highCVE-2026-63828: In the Linux kernel, the following vulnerability has been resolved: apparmor: mediate the impl…nvd

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