How severe is CVE-2026-39421?

CVE-2026-39421 has a CVSS 3.x base score of 6.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2026-39421 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-39421?

CVE-2026-39421 affects Maxkb. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-39421?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-39421 have an EU (EUVD) identifier?

Yes. CVE-2026-39421 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-22180.

When was CVE-2026-39421 published?

CVE-2026-39421 was published on 2026-04-14 and last updated on 2026-06-17.

CVE-2026-39421

CVE-2026-39421 is a medium-severity vulnerability in Maxkb with a CVSS 3.x base score of 6.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-94.

Key facts

Severity: Medium (CVSS 3.x base score 6.3)
EPSS exploit prediction: 0% (18th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-22180
Weakness: CWE-94
Affected product: Maxkb
Published: 2026-04-14
Last modified: 2026-06-17

Description

MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain a sandbox escape vulnerability in the ToolExecutor component. By leveraging Python's ctypes library to execute raw system calls, an authenticated attacker with workspace privileges can bypass the LD_PRELOAD-based sandbox.so module to achieve arbitrary code execution via direct kernel system calls, enabling full network exfiltration and container compromise. The library intercepts critical standard system functions such as execve, system, connect, and open. It also intercepts mprotect to prevent PROT_EXEC (executable memory) allocations within the sandboxed Python processes, but pkey_mprotect is not blocked. This issue has been fixed in version 2.8.0.

Frequently asked questions

What is CVE-2026-39421?: MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain a sandbox escape vulnerability in the ToolExecutor component. By leveraging Python's ctypes library to execute raw system calls, an authenticated attacker with workspace privileges can bypass the LD_PRELOAD-based sandbox.so module to achieve arbitrary code execution via direct kernel system calls, enabling full network exfiltration and container compromise. The library intercepts critical standard system functions such as execve, system, connect, and open. It also intercepts mprotect to prevent PROT_EXEC (executable memory) allocations within the sandboxed Python processes, but pkey_mprotect is not blocked. This issue has been fixed in version 2.8.0.
How severe is CVE-2026-39421?: CVE-2026-39421 has a CVSS 3.x base score of 6.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2026-39421 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-39421?: CVE-2026-39421 affects Maxkb. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-39421?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-39421 have an EU (EUVD) identifier?: Yes. CVE-2026-39421 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-22180.
When was CVE-2026-39421 published?: CVE-2026-39421 was published on 2026-04-14 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:maxkb:maxkb:*:*:*:*:-:*:*:*

More vulnerabilities in Maxkb

CVE-2025-66446 — High (CVSS 8.8): MaxKB is an open-source AI assistant for enterprise. Versions 2.3.1 and below have improper file permissions which…
CVE-2025-66419 — High (CVSS 8.8): MaxKB is an open-source AI assistant for enterprise. In versions 2.3.1 and below, the tool module allows an attacker to…
CVE-2025-48950 — High (CVSS 8.8): MaxKB is an open-source AI assistant for enterprise. Prior to version 1.10.8-lts, Sandbox only restricts the execution…
CVE-2025-64511 — High (CVSS 7.4): MaxKB is an open-source AI assistant for enterprise. In versions prior to 2.3.1, a user can access internal network…
CVE-2024-56137 — Medium (CVSS 6.8): MaxKB, which stands for Max Knowledge Base, is an open source knowledge base question-answering system based on a large…
CVE-2026-39420 — Medium (CVSS 6.3): MaxKB is an open-source AI assistant for enterprise. In versions 2.7.1 and below, an incomplete sandbox protection…

All CVEs affecting Maxkb →

Other CWE-94 (Code Injection) vulnerabilities

CVE-2026-57624 — Critical (CVSS 10.0): Unauthenticated Remote Code Execution (RCE) in Blocksy Companion Pro <= 2.1.46 versions.
CVE-2026-10134 — Critical (CVSS 10.0): IBM Langflow OSS 1.0.0 through 1.9.3 allows an attacker to read every secret available to the Langflow process, read…
CVE-2026-53576 — Critical (CVSS 10.0): Kestra is an open-source, event-driven orchestration platform. Prior to 1.0.45 and 1.3.21, the authentication filter…
CVE-2026-10561 — Critical (CVSS 10.0): IBM Langflow OSS 1.0.0 through 1.9.3 has an vulnerability due to an improper isolation of Python execution combined…
CVE-2026-25470 — Critical (CVSS 10.0): Improper Control of Generation of Code ('Code Injection') vulnerability in ACPT ACPT (Pro) - Custom Post Types Plugin…
CVE-2026-48836 — Critical (CVSS 10.0): Unauthenticated Remote Code Execution (RCE) in Easy Invoice <= 2.1.19 versions.

Browse all CWE-94 (Code Injection) vulnerabilities →