CVE-2026-34208: nyariv SandboxJS · Protection Mechanism Failure
Affects nyariv SandboxJSSource CVE Database V5
Not known to be exploited · CVSS 10.0 Critical : upgrade to 0.8.36 as a priority.
Data as of 30 Oct 2026, 06:59 UTC
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 0.8.36
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:LExploitation evidence
Disclosed: evidence found.
CVE published 6 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 29 Oct 2026.
What to do
Upgrade SandboxJS and nyariv/sandboxjs to 0.8.36.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| nyarivSandboxJS | Affected
| Fixed in
|
npmnyariv/sandboxjspkg:npm/nyariv/sandboxjsOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade SandboxJS to version 0.8.36 or later, where this vulnerability is fixed. Since the vulnerability is resolved in this version, no additional mitigation steps are required beyond applying the update. Patch status is not explicitly stated in the vendor advisory, but the description confirms the fix is included in version 0.8.36.
Description
SandboxJS is a JavaScript sandboxing library. Prior to 0.8.36, SandboxJS blocks direct assignment to global objects (for example Math.random = ...), but this protection can be bypassed through an exposed callable constructor path: this.constructor.call(target, attackerObject). Because this.constructor resolves to the internal SandboxGlobal function and Function.prototype.call is allowed, attacker code can write arbitrary properties into host global objects and persist those mutations across sandbox instances in the same process. This vulnerability is fixed in 0.8.36.