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VulnerabilityPublished Updated

CVE-2026-26954: nyariv SandboxJS · Code Injection

Affects nyariv SandboxJSSource CVE Database V5

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Not known to be exploited · CVSS 10.0 Critical : upgrade to 0.8.34 as a priority.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
10.0Critical
How severe the flaw is on the 0–10 CVSS scale.

Contested

Critical score, yet low EPSS after six months
EPSS
0.5% chance of exploitation in 30 days – higher than 46% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.8.34
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade SandboxJS and nyariv/sandboxjs to 0.8.34.

Affected software

ProductAffectedFixed in
nyarivSandboxJSAffected
  • <0.8.34
Fixed in
  • 0.8.34
npmnyariv/sandboxjspkg:npm/nyariv/sandboxjsOther threatsAffected
  • <0.8.34
Fixed in
  • 0.8.34

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2026-26954, organizations should immediately upgrade all instances of nyariv SandboxJS to version 0.8.34 or later, where the vulnerability is patched. Additionally, review and audit any custom sandboxing implementations or wrappers around SandboxJS to ensure they do not inadvertently expose the Function constructor or allow Object.fromEntries misuse. Implement strict input validation and sanitization for any data processed within sandboxed environments to reduce the risk of injection attacks. Employ runtime monitoring and anomaly detection to identify suspicious code execution patterns indicative of sandbox escapes. Where possible, isolate sandboxed environments further using containerization or virtualization to limit the blast radius of potential exploits. Maintain an inventory of all applications and services using SandboxJS to ensure comprehensive patching. Finally, stay informed about updates from the vendor and security advisories related to SandboxJS and similar sandboxing libraries.

Description

SandboxJS is a JavaScript sandboxing library. Prior to 0.8.34, it is possible to obtain arrays containing Function, which allows escaping the sandbox. Given an array containing Function, and Object.fromEntries, it is possible to construct {[p]: Function} where p is any constructible property. This vulnerability is fixed in 0.8.34.

References

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