Time-of-check Time-of-use (TOCTOU) Race Condition in handlebars.js - #VU124846
Published: April 2, 2026
Vulnerability identifier: #VU124846
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: N/A
CWE-ID: CWE-367
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: The Handlebars Templating Language
Affected software:
handlebars.js
handlebars.js
Detailed vulnerability description
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to a time-of-check time-of-use race condition in the container.lookup function in lib/handlebars/runtime.js when processing property lookups with the compat compile option enabled. A remote attacker can trigger a crafted property lookup to disclose sensitive information.
This issue affects handlebars.js when {compat: true} enables depthedLookup, and the vulnerable code validates access through lookupProperty() but then performs a separate raw property read.
Remediation
Install security update from vendor's website.