1. Home
  2. Vulnerabilities
  3. CVE-2026-63828
0.0
NA
CVE-2026-63828
apparmor: mediate the implicit connect of TCP fast open sendmsg
Overview
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.

Details
INFO

Published Date :

July 19, 2026, 12:16 p.m.

Last Modified :

July 19, 2026, 12:16 p.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Impact
Affected Products

The following products are affected by CVE-2026-63828 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

No affected product recoded yet

: Total Affected Vendor : 0 | Products : 0
Solution
Update the Linux kernel to address the AppArmor TCP fast open implicit connect vulnerability.
  • Update the Linux kernel to the latest stable version.
  • Verify AppArmor profiles enforce connection restrictions.
  • Reboot the system after kernel update.
  • Test applications for correct network connectivity.
References
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-63828.

URL Resource
https://git.kernel.org/stable/c/07b71c342382b854ab8030b244aeab6a7228ad7d
https://git.kernel.org/stable/c/45ebb934ea50b436ce49b2f159f090dab0d7fa28
https://git.kernel.org/stable/c/4a69b83045d3195d5b9a9b053ad840ddb2998b4e
https://git.kernel.org/stable/c/4d587cd8a72155089a627130bbd4716ec0856e21
https://git.kernel.org/stable/c/7f57428ce00891d26b0f087ef754a4d820ec83aa
https://git.kernel.org/stable/c/faea60deaa05c76f0772650f42eafde12bd39d93
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-63828 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-63828 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-63828 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-63828 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Jul. 19, 2026

    Action Type Old Value New Value
    Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'cf60af03ca4e71134206809ea892e49b92a88896', 'lessThan': '7f57428ce00891d26b0f087ef754a4d820ec83aa', 'versionType': 'git'}, {'status': 'affected', 'version': 'cf60af03ca4e71134206809ea892e49b92a88896', 'lessThan': 'faea60deaa05c76f0772650f42eafde12bd39d93', 'versionType': 'git'}, {'status': 'affected', 'version': 'cf60af03ca4e71134206809ea892e49b92a88896', 'lessThan': '07b71c342382b854ab8030b244aeab6a7228ad7d', 'versionType': 'git'}, {'status': 'affected', 'version': 'cf60af03ca4e71134206809ea892e49b92a88896', 'lessThan': '4a69b83045d3195d5b9a9b053ad840ddb2998b4e', 'versionType': 'git'}, {'status': 'affected', 'version': 'cf60af03ca4e71134206809ea892e49b92a88896', 'lessThan': '45ebb934ea50b436ce49b2f159f090dab0d7fa28', 'versionType': 'git'}, {'status': 'affected', 'version': 'cf60af03ca4e71134206809ea892e49b92a88896', 'lessThan': '4d587cd8a72155089a627130bbd4716ec0856e21', 'versionType': 'git'}], 'programFiles': ['security/apparmor/lsm.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3.6'}, {'status': 'unaffected', 'version': '0', 'lessThan': '3.6', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.1.177', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.144', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.95', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.38', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.3', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['security/apparmor/lsm.c'], 'defaultStatus': 'affected'}]
    Added 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.
    Added Reference https://git.kernel.org/stable/c/07b71c342382b854ab8030b244aeab6a7228ad7d
    Added Reference https://git.kernel.org/stable/c/45ebb934ea50b436ce49b2f159f090dab0d7fa28
    Added Reference https://git.kernel.org/stable/c/4a69b83045d3195d5b9a9b053ad840ddb2998b4e
    Added Reference https://git.kernel.org/stable/c/4d587cd8a72155089a627130bbd4716ec0856e21
    Added Reference https://git.kernel.org/stable/c/7f57428ce00891d26b0f087ef754a4d820ec83aa
    Added Reference https://git.kernel.org/stable/c/faea60deaa05c76f0772650f42eafde12bd39d93
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CVSS
Vulnerability Scoring Details
No CVSS metrics available for this vulnerability.