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CVE-2026-25881VulnerabilityPublished

CVE-2026-25881: nyariv SandboxJS · Prototype Pollution

Affects nyariv SandboxJSSource CVE Database V5

0

Not known to be exploited · CVSS 9.1 Critical : upgrade to 0.8.31 as a priority.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score
9.1Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.6% chance of exploitation in 30 days – higher than 49% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.8.31
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 9 Feb 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 2026-10-25.

What to do

Upgrade nyariv SandboxJS to 0.8.31.

Affected software

ProductAffectedFixed in
nyarivSandboxJSAffected
  • <0.8.31
Fixed in
  • 0.8.31

AI-suggested

1. Immediately upgrade all instances of SandboxJS to version 0.8.31 or later, where the vulnerability is fixed. 2. Audit all applications and services that use SandboxJS to identify and isolate vulnerable versions. 3. Implement strict input validation and sanitization for any code or data executed within SandboxJS to reduce the risk of malicious payloads. 4. Employ runtime monitoring and anomaly detection to identify unusual prototype modifications or suspicious execSync usage. 5. Restrict the use of sensitive functions like execSync within sandboxed environments or replace them with safer alternatives. 6. Use additional sandboxing or containerization layers to limit the impact of potential escapes. 7. Conduct regular security reviews and penetration testing focused on prototype pollution and sandbox escape vectors. 8. Educate developers about secure coding practices related to prototype pollution and sandbox usage.

Description

CVE-2026-25881 is a critical prototype pollution vulnerability in SandboxJS versions prior to 0.8.31. It allows sandboxed JavaScript code to escape isolation by mutating host built-in prototypes such as Map.prototype or Set.prototype. This occurs because the isGlobal protection flag is improperly stripped when global prototype references are passed through array literals, enabling persistent prototype pollution. Exploiting this flaw can lead to remote code execution (RCE) if polluted properties are used in sensitive operations like execSync. The vulnerability has a CVSS score of 9.1, indicating high severity, and affects applications relying on SandboxJS for secure code execution.

References

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