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Review reviewHigh

CVE-2026-63828

Linux

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() (n...

CVSS
8.4
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.19
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 8.4

Vulnerability overview

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() (n...

Affected product and versions

Product
Linux
Affected versions
>= cf60af03ca4e71134206809ea892e49b92a88896 < a16714e7cf2baa98ba2efddd5d6cbac641f4e76b, >= cf60af03ca4e71134206809ea892e49b92a88896 < 20383429b56974507c465d016e5238b189f7a246, >= cf60af03ca4e71134206809ea892e49b92a88896 < 7f57428ce00891d26b0f087ef754a4d820ec83aa, >= cf60af03ca4e71134206809ea892e49b92a88896 < faea60deaa05c76f0772650f42eafde12bd39d93, >= cf60af03ca4e71134206809ea892e49b92a88896 < 07b71c342382b854ab8030b244aeab6a7228ad7d, >= cf60af03ca4e71134206809ea892e49b92a88896 < 4a69b83045d3195d5b9a9b053ad840ddb2998b4e, >= cf60af03ca4e71134206809ea892e49b92a88896 < 45ebb934ea50b436ce49b2f159f090dab0d7fa28, >= cf60af03ca4e71134206809ea892e49b92a88896 < 4d587cd8a72155089a627130bbd4716ec0856e21, >= 3.6
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
CWE
Not available