CVE intelligence

CVE-2026-63828

Vulnerability intelligence

Published Jul 19, 2026Sources checked Oct 28, 2026

8.4HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-63828 and is rated High severity with a CVSS score of 8.4. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Aug 14, 2026

CBL-Mariner Releases

Vendor-listed releases

6.6.150.1-1

CISA KEVNot listedBased on the latest collected catalog

EPSS0.2%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-63828?

In the Linux kernel, the following vulnerability has been resolved:

apparmor: mediate the implicit connect of TCP fast open sendmsg

sendmsg()/sendto() with MSG_FASTOPEN is a combination of connect(2) and write(2): it opens the connection in the SYN. apparmor_socket_sendmsg() only checks AA_MAY_SEND, so a profile that grants send but denies connect lets a confined task open an outbound TCP/MPTCP connection that connect(2) would have refused, bypassing connect mediation.

Mediate the implicit connect when MSG_FASTOPEN is set and a destination is supplied. Add it to apparmor_socket_sendmsg() (not the shared aa_sock_msg_perm() helper, which recvmsg also uses) and call aa_sk_perm() directly, mirroring the selinux and tomoyo fixes. sk_is_tcp() does not cover MPTCP fast open, so the SOCK_STREAM/IPPROTO_MPTCP arm is explicit.

Source: NVD