CVE-2026-63828

AppArmor connect-policy bypass via TCP Fast Open

Published Jul 19, 2026 · Updated Jul 19, 2026

Access-control bypass in the Linux Kernel allows local users to open outbound TCP or MPTCP connections denied by AppArmor policy. apparmor_socket_sendmsg() checks only AA_MAY_SEND and omits connect permission when sendmsg() or sendto() supplies a destination with MSG_FASTOPEN. Exploitation requires a confined task whose profile permits sending but denies connecting, allowing unauthorized outbound network access without escaping the host or interrupting service.

CVSS severity8.4
High
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Access-control bypass in the Linux Kernel allows local users to open outbound TCP or MPTCP connections denied by AppArmor policy. apparmor_socket_sendmsg() checks only AA_MAY_SEND and omits connect permission when sendmsg() or sendto() supplies a destination with MSG_FASTOPEN. Exploitation requires a confined task whose profile permits sending but denies connecting, allowing unauthorized outbound network access without escaping the host or interrupting service.

The record

CVE
CVE-2026-63828
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-1220
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.6
  2. Affected versionversion=cf60af03ca4e71134206809ea892e49b92a88896 <07b71c342382b854ab8030b244aeab6a7228ad7d
  3. Affected versionversion=cf60af03ca4e71134206809ea892e49b92a88896 <45ebb934ea50b436ce49b2f159f090dab0d7fa28
  4. Affected versionversion=cf60af03ca4e71134206809ea892e49b92a88896 <4a69b83045d3195d5b9a9b053ad840ddb2998b4e
  5. Affected versionversion=cf60af03ca4e71134206809ea892e49b92a88896 <4d587cd8a72155089a627130bbd4716ec0856e21
  6. Affected versionversion=cf60af03ca4e71134206809ea892e49b92a88896 <7f57428ce00891d26b0f087ef754a4d820ec83aa
  7. Affected versionversion=cf60af03ca4e71134206809ea892e49b92a88896 <faea60deaa05c76f0772650f42eafde12bd39d93

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=3.6; version=cf60af03ca4e71134206809ea892e49b92a88896 <07b71c342382b854ab8030b244aeab6a7228ad7d; version=cf60af03ca4e71134206809ea892e49b92a88896 <45ebb934ea50b436ce49b2f159f090dab0d7fa28; version=cf60af03ca4e71134206809ea892e49b92a88896 <4a69b83045d3195d5b9a9b053ad840ddb2998b4e; version=cf60af03ca4e71134206809ea892e49b92a88896 <4d587cd8a72155089a627130bbd4716ec0856e21; version=cf60af03ca4e71134206809ea892e49b92a88896 <7f57428ce00891d26b0f087ef754a4d820ec83aa; version=cf60af03ca4e71134206809ea892e49b92a88896 <faea60deaa05c76f0772650f42eafde12bd39d93

Published CVSS scores

8.4LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1220Insufficient Granularity of Access Control

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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