What is CVE-2026-39418?

CVE-2026-39418 is a High severity Linux kernel vulnerability with a CVSS score of 7.4 out of 10. CVE-2026-39418 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-39418?

CVE-2026-39418 has a CVSS score of 7.4 out of 10, rated High severity. The vector string is CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L.

Is there a patch available for CVE-2026-39418?

No patch is currently available for CVE-2026-39418. Monitor the NIST NVD and your Linux distribution's security advisories for updates.

Is CVE-2026-39418 actively exploited?

CVE-2026-39418 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-39418

High

MaxKB is an open-source AI assistant for enterprise. In versions 2.7.1 and below, sandbox network protection can be bypassed by using socket.sendto() with the MSG_FASTOPEN flag. This allows authenticated user with tool-editing permissions to reach internal services that are explicitly blocked by the sandbox's banned hosts configuration. MaxKB's sandbox uses LD_PRELOAD to hook the connect() function and block connections to banned IPs, but Linux's sendto() with the MSG_FASTOPEN flag can establish TCP connections directly through the kernel without ever calling connect(), completely bypassing the IP validation. Although sendto is listed in the syscall() wrapper, this is ineffective because glibc invokes the kernel syscall directly rather than routing through the hooked syscall() function. This issue has been fixed in version 2.8.0.

Package Linux Kernel

Published 2026-04-14

Last modified 2026-04-20

CVSS version 3.1

Patch available

Awaiting data

CVSS 3.1 score

7.4

out of 10

High

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

Low

Vector string

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L

Weakness type

CWE-918

CVE-2026-39418 is classified as CWE-918

See CWE-918 on MITRE CWE for full details on this weakness type.

References

The following references provide additional information about CVE-2026-39418 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

GitHub
https://github.com/1Panel-dev/MaxKB/releases/tag/v2.8.0

Release Notes
GitHub
https://github.com/1Panel-dev/MaxKB/security/advisories/GHSA-w9g4-q3gm-6q6w

Vendor Advisory
Kernel patch commit
https://github.com/1Panel-dev/MaxKB/commit/4d06362750b15390437f1d2e4d14ec79baef8559
Patch

Details

CVE ID CVE-2026-39418

Severity High

CVSS score 7.4 / 10

CVSS version 3.1

Published 2026-04-14

Modified 2026-04-20

KEV No

Patch Awaiting data

Package linux

Frequently asked questions

What is CVE-2026-39418?

CVE-2026-39418 is a High severity Linux kernel vulnerability with a CVSS score of 7.4 out of 10 . CVE-2026-39418 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-39418?

CVE-2026-39418 has a CVSS score of 7.4 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L.
Is there a patch available for CVE-2026-39418?

No patch is currently available for CVE-2026-39418. Monitor the NIST NVD and your Linux distribution's security advisories for updates.
Is CVE-2026-39418 actively exploited?

No — CVE-2026-39418 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.