CVE-2026-25586 json
SandboxJS has a Sandbox Escape via Prototype Whitelist Bypass and Host Prototype Pollution
published 9mo ago modified 4mo ago also EUVD-2026-5592 , GHSA-jjpw-65fv-8g48
- cvss
- 10.0
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.7%
- EPSS 0.7% chance of exploitation in 30 days, percentile 53%
- public exploits
- 0
- none known
Summary
SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, a sandbox escape is possible by shadowing hasOwnProperty on a sandbox object, which disables prototype whitelist enforcement in the property-access path. This permits direct access to __proto__ and other blocked prototype properties, enabling host Object.prototype pollution and persistent cross-sandbox impact. This vulnerability is fixed in 0.8.29.
Patch / fix
Is CVE-2026-25586 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- total
- Assessed
- 9mo ago
Exploit prediction
0.69% chance of exploitation in the next 30 days, higher than 53% of all scored CVEs (FIRST EPSS, 2026-11-09).
Exploits and checks
- github.com https://github.com/nyariv/SandboxJS/security/advisories/GHSA-jjpw-65fv-8g48 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 10.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
| GitHub | 3.1 | 10.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | @nyariv/sandboxjs | <0.8.29 |
0.8.29 |
Affected products
- nyariv SandboxJS
Classification
- Weakness
-
- CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component
References
-
github.com
/nyariv/SandboxJS/commit/67cb186c41c78c51464f70405504e8ef0a6e43c3
web, patch
-
github.com
/nyariv/SandboxJS/security/advisories/GHSA-jjpw-65fv-8g48
exploit, web, vendor-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-25586
advisory
-
github.com
/nyariv/SandboxJS
package
Sources
- CVE List CVE-2026-25586
- GitHub Advisory GHSA-jjpw-65fv-8g48
- NVD CVE-2026-25586
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.