CVE-2026-39421

MEDIUMNVD 6.36.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.3 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 73% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
6.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.3Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
6.3
EG Score
6.3(medium)
EPSS
18.0%
KEV
Not listed

Published

April 14, 2026

Last Modified

April 20, 2026

References (3)

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 38× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-16 17:03 UTCEPSS rescore
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Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-39421?
CVE-2026-39421 is a medium vulnerability published on April 14, 2026. 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 LDPRELOAD-based…
When was CVE-2026-39421 disclosed?
CVE-2026-39421 was first published in the National Vulnerability Database on April 14, 2026, with the most recent update on April 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-39421 actively exploited?
CVE-2026-39421 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 18.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-39421?
CVE-2026-39421 has a CVSS v3 base score of 6.3 (NVD).
How do I remediate CVE-2026-39421?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-39421, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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