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EPSS 0.1%top 97%

In the Linux kernel, the following vulnerability has been resolved: apparmor: mediate the implicit connect of TCP fast open sendmsg… (CVE-2026-63828)

0
Medium
Published: 07/19/2026 (07/19/2026, 12:16:00 UTC)
Source: GCVE Database
Product: linux

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.

CVSS v3.1

Score 8.4high

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
None
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

Affected software

Affected versions
MicrosoftAzure Linux3.0Azure Linux 3.0kernel

Technical Details

Gcve Source
db.gcve.eu
Osv Id
GHSA-fvhv-v8p3-vrwq
Osv Schema Version
1.4.0
Aliases
["CVE-2026-63828"]
Ecosystems
[]
Database Specific Severity
null
Cvss Version
3.1

Threat ID: 6a5d27ad2a4a8d598913125d

Added to database: 07/19/2026, 19:38:21 UTC

Last enriched: 08/15/2026, 03:28:49 UTC

Last updated: 09/03/2026, 22:52:13 UTC

Views: 62

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