CVE-2026-63828

apparmor: mediate the implicit connect of TCP fast open sendmsg

State: Published
Severity: 8.4 High
Published: Jul 19, 2026
Updated: Aug 17, 2026
Reserved: Jul 19, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	8.4 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	cf60af03ca4e71134206809ea892e49b92a88896 to before a16714e7cf2baa98ba2efddd5d6cbac641f4e76bAffected cf60af03ca4e71134206809ea892e49b92a88896 to before 20383429b56974507c465d016e5238b189f7a246Affected cf60af03ca4e71134206809ea892e49b92a88896 to before 7f57428ce00891d26b0f087ef754a4d820ec83aaAffected cf60af03ca4e71134206809ea892e49b92a88896 to before faea60deaa05c76f0772650f42eafde12bd39d93Affected cf60af03ca4e71134206809ea892e49b92a88896 to before 07b71c342382b854ab8030b244aeab6a7228ad7dAffected cf60af03ca4e71134206809ea892e49b92a88896 to before 4a69b83045d3195d5b9a9b053ad840ddb2998b4eAffected cf60af03ca4e71134206809ea892e49b92a88896 to before 45ebb934ea50b436ce49b2f159f090dab0d7fa28Affected cf60af03ca4e71134206809ea892e49b92a88896 to before 4d587cd8a72155089a627130bbd4716ec0856e21Affected
LinuxLinux	3.6Affected before 3.6Not affected 5.10.261 through 5.10.Not affected 5.15.212 through 5.15.Not affected 6.1.177 through 6.1.Not affected 6.6.144 through 6.6.Not affected 6.12.95 through 6.12.Not affected 6.18.38 through 6.18.Not affected 7.1.3 through 7.1.*Not affected 7.2 and laterNot affected

Product

Versions

LinuxLinux

cf60af03ca4e71134206809ea892e49b92a88896 to before a16714e7cf2baa98ba2efddd5d6cbac641f4e76bAffected
cf60af03ca4e71134206809ea892e49b92a88896 to before 20383429b56974507c465d016e5238b189f7a246Affected
cf60af03ca4e71134206809ea892e49b92a88896 to before 7f57428ce00891d26b0f087ef754a4d820ec83aaAffected
cf60af03ca4e71134206809ea892e49b92a88896 to before faea60deaa05c76f0772650f42eafde12bd39d93Affected
cf60af03ca4e71134206809ea892e49b92a88896 to before 07b71c342382b854ab8030b244aeab6a7228ad7dAffected
cf60af03ca4e71134206809ea892e49b92a88896 to before 4a69b83045d3195d5b9a9b053ad840ddb2998b4eAffected
cf60af03ca4e71134206809ea892e49b92a88896 to before 45ebb934ea50b436ce49b2f159f090dab0d7fa28Affected
cf60af03ca4e71134206809ea892e49b92a88896 to before 4d587cd8a72155089a627130bbd4716ec0856e21Affected

LinuxLinux

3.6Affected
before 3.6Not affected
5.10.261 through 5.10.*Not affected
5.15.212 through 5.15.*Not affected
6.1.177 through 6.1.*Not affected
6.6.144 through 6.6.*Not affected
6.12.95 through 6.12.*Not affected
6.18.38 through 6.18.*Not affected
7.1.3 through 7.1.*Not affected
7.2 and laterNot affected

References

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