File disclosure via user-controlled layout option
Published May 14, 2021 · Updated Aug 3, 2024
File disclosure in Express Handlebars 5.3.2 and earlier allows remote attackers to read files via a user-controlled layout option. The engine accepts layout alongside template data and resolves an attacker-supplied filename as a layout, returning its contents in rendered output. Exploitation requires a downstream Express route to pass user-controlled objects directly to res.render; readable files need an existing extension.
Summary
What happened
File disclosure in Express Handlebars 5.3.2 and earlier allows remote attackers to read files via a user-controlled layout option. The engine accepts layout alongside template data and resolves an attacker-supplied filename as a layout, returning its contents in rendered output. Exploitation requires a downstream Express route to pass user-controlled objects directly to res.render; readable files need an existing extension.
The record
- CVE
- CVE-2021-32820
- Published
- May 14, 2021
- Updated
- Aug 3, 2024
- Vendor
- Express Handlebars
- Product
- Express Handlebars
- Classifications
- CWE-200, CWE-94, T1005
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 14, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record 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.
- Affected versionversion=<= 5.3.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- GitHub Security Lab layout file-disclosure proof of conceptproof of concept · demonstrated
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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