Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HSummary
CVE-2026-25641 is a critical-severity Time-of-check Time-of-use (TOCTOU) Race Condition (CWE-367) vulnerability in Nyariv Sandboxjs. Its CVSS base score is 10.0 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Path Interception (T1034); ranked at the 40th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to AC-25 (Reference Monitor) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-25641 is a sandbox escape vulnerability in SandboxJS, an open-source JavaScript sandboxing library. Versions prior to 0.8.29 are affected due to a mismatch between the key used for validation via hasOwnProperty(key) and the key employed for actual property access. Although property access keys are annotated as strings, this type enforcement is not implemented, enabling attackers to supply malicious objects that coerce to different string values during validation versus access phases. The issue is classified under CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition) and carries a CVSS v3.1 base score of 10.0 (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H), indicating critical severity.
Remote, unauthenticated attackers can exploit this vulnerability over the network with low complexity and no user interaction required. By providing specially crafted objects to the sandboxed execution environment, attackers bypass security checks, achieving sandbox escape. Successful exploitation grants high-impact access to confidentiality, integrity, and availability, potentially allowing arbitrary code execution within the host JavaScript context.
The vulnerability is addressed in SandboxJS version 0.8.29, as detailed in the project's security advisory (GHSA-7x3h-rm86-3342) and the fixing commit (67cb186c41c78c51464f70405504e8ef0a6e43c3), which resolves the key coercion issue in executor.ts around line 304. Security practitioners should update to 0.8.29 or later and review integrations using SandboxJS for exposure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-5589
Vulnerability Data
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…
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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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V15.4.2V17.2.6
Mitigating Controls (NIST 800-53 r5) AI
A reference monitor that is always invoked and analyzable structurally eliminates the non-atomic check-then-use pattern underlying TOCTOU.
Access enforcement that performs an atomic check-and-use decision directly stops the window in which a TOCTOU race can be exploited.
Process isolation limits the blast radius of a successful TOCTOU exploitation but does not remove the race itself.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly include coding standards and reviews that prevent TOCTOU race conditions.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Reliable, synchronized time across systems narrows the exploitable window in which a resource state can change between a security check and its use.