CVE-2026-33937 | Vulnerability Intelligence

Stored catalog record

Source record retrieved 2026-10-28T10:18:21.763309+00:00. Scheduled imports handle updates; this page does not assert that the provider was queried just now.

Vulnerability overview

Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, `Handlebars.compile()` accepts a pre-parsed AST object in addition to a template string. The `value` field of a `NumberLiteral` AST node is emitted directly into the generated JavaScript without quoting or sanitization. An attacker who can supply a crafted AST to `compile()` can therefore inject and execute arbitrary JavaScript, leading to Remote Code Execution on the server. Version 4.7.9 fixes the issue. Some workarounds are available. Validate input type before calling `Handlebars.compile()`; ensure the argument is always a `string`, never a plain object or JSON-deserialized value. Use the Handlebars runtime-only build (`handlebars/runtime`) on the server if templates are pre-compiled at build time; `compile()` will be unavailable.

Patch review priority

Critical technical severity

CVSS is at least 9.0; exploitation is not established by severity alone.

FIRST EPSS: 1.91% · percentile 79.7 · score date 2026-10-27.

EPSS estimates probability of exploitation in the next 30 days. It does not measure your exposure or prove exploitation. The elevated threshold is 10%; CISA KEV takes precedence. About FIRST EPSS ↗

Severity and scoring

CVSS score: 9.8 · CRITICAL
CVSS version: 3.1
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weaknesses: CWE-843, CWE-94

CVSS measures technical severity; it does not establish whether this vulnerability is being exploited in your environment.

Known exploitation and remediation

Not listed in the CISA catalog retrieved for this record. This does not establish that exploitation has not occurred.

Verify affected versions and patch availability in the vendor advisory before making changes.

Affected products and versions

cpe:2.3:a:handlebarsjs:handlebars:*:*:*:*:*:node.js:*:*
From (inclusive): 4.0.0
Before (exclusive): 4.7.9

These are NVD CPE applicability entries. Some products depend on configuration conditions; consult the official record to confirm applicability.

Advisories and references

Explore official sources

Read the official NVD record ↗

Explore the CISA catalog ↗

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