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.
Affected versions
Linux kernel versions
3.6
and later are affected. Fixed in
6.1.177,
6.6.144,
6.12.95,
6.18.38,
7.1.3,
7.2-rc1
and their respective stable series.
References
6 totalFrequently asked questions
-
What is CVE-2026-63828?
CVE-2026-63828 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 3.6 onward and has been patched in 6.1.177, 6.6.144, 6.12.95 and others. CVE-2026-63828 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
-
Is there a patch available for CVE-2026-63828?
Yes — CVE-2026-63828 has been patched. Fixed versions include 6.1.177, 6.6.144, 6.12.95 and others. If you are running Linux kernel 3.6 or later up to the fix versions, apply the relevant patch for your kernel branch.
-
Is CVE-2026-63828 actively exploited?
No — CVE-2026-63828 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.