CVE-2026-77521
CVE-2026-77521 is a critical-severity vulnerability with a CVSS 3.x base score of 10.0. The underlying weakness is classified as CWE-78.
Key facts
- Severity: Critical (CVSS 3.x base score 10.0)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-78
- Published:
- Last modified:
Description
MaxKB is an open-source AI assistant for enterprise. Prior to version 2.10.5-lts, assistants with a tool, MCP tool, skill, or sub-application use SandboxShellBackend, which exposes an execute shell tool without excluding it and omits execute from interrupt_on, so human approval is not required. Untrusted chat or ingested content can therefore cause command execution; source deployments with MAXKB_SANDBOX disabled run commands directly as the application user, while the official root container's string-based gosu wrapper allowed shell metacharacters to execute outside the intended sandbox. This issue is fixed in version 2.10.5-lts.
Frequently asked questions
- What is CVE-2026-77521?
- MaxKB is an open-source AI assistant for enterprise. Prior to version 2.10.5-lts, assistants with a tool, MCP tool, skill, or sub-application use SandboxShellBackend, which exposes an execute shell tool without excluding it and omits execute from interrupt_on, so human approval is not required. Untrusted chat or ingested content can therefore cause command execution; source deployments with MAXKB_SANDBOX disabled run commands directly as the application user, while the official root container's string-based gosu wrapper allowed shell metacharacters to execute outside the intended sandbox. This issue is fixed in version 2.10.5-lts.
- How severe is CVE-2026-77521?
- CVE-2026-77521 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2026-77521 being actively exploited?
- It is not currently listed in CISA's Known Exploited Vulnerabilities catalog, and no EPSS exploit-prediction score is available yet.
- How do I fix CVE-2026-77521?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2026-77521 published?
- CVE-2026-77521 was published on 2026-09-21.
References
- https://github.com/1Panel-dev/MaxKB/commit/594f50f2ea80a502d1c955371ba0438b277c30ea
- https://github.com/1Panel-dev/MaxKB/releases/tag/v2.10.5-lts
- https://github.com/1Panel-dev/MaxKB/security/advisories/GHSA-f36j-f34j-h3rx
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