CVE-2026-39418: MaxKB is an open-source AI assistant for enterprise. In versions 2.7.1 and below, sandbox network protection can be…
CVE-2026-39418 · Severity: medium · CVSS 5 · Published 2026-04-14
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.
No. Junglewise Threat Intelligence has no report of CVE-2026-39418 being exploited in the wild.
How severe is CVE-2026-39418?
Medium severity, with a CVSS score of 5, published 14 April 2026.
Which products and versions are affected?
Maxkb. The advisory does not name versions.
Is there a fix for CVE-2026-39418?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
Am I affected by CVE-2026-39418?
Check whether you run Maxkb. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.