Sandboxjs
CVE-2026-25641
CRITICAL
GHSA-7x3h-rm86-3342
Severity by source
AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Primary rating from GitHub Advisory · only source for this CVE.
CVSS VectorGitHub Advisory
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Lifecycle Timeline
4DescriptionGitHub Advisory
SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, there is a sandbox escape vulnerability due to a mismatch between the key on which the validation is performed and the key used for accessing properties. Even though the key used in property accesses is annotated as string, this is never enforced. So, attackers can pass malicious objects that coerce to different string values when used, e.g., one for the time the key is sanitized using hasOwnProperty(key) and a different one for when the key is used for the actual property access. This vulnerability is fixed in 0.8.29.
AnalysisAI
SandboxJS has a fifth CVSS 10.0 escape via a TOCTOU race condition in sandbox validation, allowing code to slip through during the check-execute gap.
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | No special conditions — remote unauthenticated exploitation against SandboxJS versions prior to 0.8.29 with default configuration accepting user-supplied objects as property keys. Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | CVSS 10.0 with PoC and patch. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker exploits the timing window between sandbox validation and code execution to modify the code that runs, bypassing all restrictions. |
| Remediation | Update to 0.8.29+ immediately. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Inventory all systems and applications using SandboxJS and identify current versions; establish incident response readiness. …
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External POC / Exploit Code
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