CVE-2026-34211Public exploitNetwork attack vector

Process crash via unbounded parser recursion

Published Apr 6, 2026 · Updated Apr 6, 2026

Uncontrolled recursion in nyariv SandboxJS before 0.8.36 allows remote attackers to crash Node.js processes via deeply nested expressions. The parser's restOfExp and lispify/lispifyExpr paths recurse on nested brackets without tracking or limiting depth. Exposure requires an application to pass attacker-controlled JavaScript into a public parsing API; successful input terminates the host process and interrupts its service.

CVSS severity6.9
Medium
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled recursion in nyariv SandboxJS before 0.8.36 allows remote attackers to crash Node.js processes via deeply nested expressions. The parser's restOfExp and lispify/lispifyExpr paths recurse on nested brackets without tracking or limiting depth. Exposure requires an application to pass attacker-controlled JavaScript into a public parsing API; successful input terminates the host process and interrupts its service.

The record

CVE
CVE-2026-34211
Published
Apr 6, 2026
Updated
Apr 6, 2026
Vendor
nyariv
Product
SandboxJS
Classifications
CWE-674, CAPEC-231, CAPEC-230, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.8.36

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

nyariv · SandboxJSversion=< 0.8.36

Published CVSS scores

6.9GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-674Uncontrolled Recursion
CAPEC-231Oversized Serialized Data Payloads
CAPEC-230Serialized Data with Nested Payloads
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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