CVE-2026-77521

CRITICALPre-NVD 10.010.0—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 10.0 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 1.0%, top 37% 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, secondary
Trending — 3 sources updated this weekElevated
10.0EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 10.0Exploit: Elevated riskExposed: 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. 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.

CVSS v3
10.0
EG Score
10.0(medium)
EG Risk
76(Attend)
EG Risk 76/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity100% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
63%
KEV
Not listed

Published

September 21, 2026

Last Modified

September 22, 2026

Advisory Details (3)

Auto-updated Sep 22, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github.
github Patch Available🟡 PoC Available

Prompt-injectable agent can lead to command execution · Advisory · 1Panel-dev/MaxKB · GitHub

https://github.com/1Panel-dev/MaxKB/security/advisories/GHSA-f36j-f34j-h3rx
github_release Patch Available

Release v2.10.5-lts (1Panel-dev/MaxKB)

Patch available: 1Panel-dev/MaxKB v2.10.5-lts

https://github.com/1Panel-dev/MaxKB/releases/tag/v2.10.5-lts
github_commit Patch Available

commit 594f50f2ea80 (1Panel-dev/MaxKB)

Patch available: 1Panel-dev/MaxKB v2.10.5-lts (contains commit 594f50f2ea80)

https://github.com/1Panel-dev/MaxKB/commit/594f50f2ea80a502d1c955371ba0438b277c30ea

Weakness Classification(3)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 9× 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. 2026-09-23 19:15 UTCEG score recompute
  2. 2026-09-23 17:54 UTCEPSS rescore
  3. 2026-09-22 18:28 UTCEG score recompute
  4. 2026-09-22 16:01 UTCEPSS rescore
  5. 2026-09-22 14:20 UTCEG score recompute
  6. 2026-09-22 13:36 UTCEG score recompute
  7. 2026-09-21 21:22 UTCEG score recompute
  8. 2026-09-21 20:48 UTCEG score recompute
  9. 2026-09-21 20:47 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-77521?
CVE-2026-77521 is a critical vulnerability published on September 21, 2026. 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 interrupton, so human approval is not required.…
When was CVE-2026-77521 disclosed?
CVE-2026-77521 was first published in the National Vulnerability Database on September 21, 2026, with the most recent update on September 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-77521 actively exploited?
CVE-2026-77521 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 37.2% of all scored CVEs.
What is the CVSS score of CVE-2026-77521?
CVE-2026-77521 has a CVSS v3 base score of 10.0 (NVD).
How do I remediate CVE-2026-77521?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-77521, 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.

Dependency Blast Radius

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