GHSA-62gr-4qp9-h98f CVE-2019-20922 SNYK-JS-HANDLEBARS-480388
Regular Expression Denial of Service in Handlebars
High
npm
- Severity
- 7.5 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 3.69%
- Chance of exploitation in the next 30 days. Higher than 89.71% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-400 Uncontrolled Resource Consumption
- Fix
4.4.5- Upgrade handlebars to this version or later
Description
Handlebars before 4.4.5 allows Regular Expression Denial of Service (ReDoS) because of eager matching. The parser may be forced into an endless loop while processing crafted templates. This may allow attackers to exhaust system resources.
Affected versions
npm
| Package | Vulnerable | Fixed in |
|---|---|---|
| handlebars | >= 4.0.0, < 4.4.5 |
4.4.5 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
handlebars npm → 4.4.5
- npm
npm install handlebars@4.4.5- yarn
yarn add handlebars@4.4.5- pnpm
pnpm add handlebars@4.4.5
Severity breakdown
CVSS 3.1 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Weakness
CWE-400: Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource.
How to prevent it
- Architecture and Design: Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
- Architecture and Design: Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution is simply difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
- Architecture and Design: Ensure that protocols have specific limits of scale placed on them.
- Implementation: Ensure that all failures in resource allocation place the system into a safe posture.
References
Advisories
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-8r5x-fm3f-whwj Handlebars: JavaScript Injection via AST Type Confusion in compile (bypass of CVE-2026-33937) | Critical | Also affects handlebars |
| GHSA-p8wg-vrv2-v86f Handlebars: JavaScript Injection via Own Property Check Bypass | Critical | Also affects handlebars |
| GHSA-xw65-4hp5-5hc7 Handlebars: JavaScript Injection via Unsafe Inline Embedding of Precompiled Templates | Medium | Also affects handlebars |
| GHSA-7rx3-28cr-v5wh Handlebars.js has a Prototype Method Access Control Gap via Missing __lookupSetter__ Blocklist Entry | Medium | Also affects handlebars |
| GHSA-442j-39wm-28r2 Handlebars.js has a Property Access Validation Bypass in container.lookup | Low | Also affects handlebars |
| GHSA-xjpj-3mr7-gcpf Handlebars.js has JavaScript Injection in CLI Precompiler via Unescaped Names and Options | High | Also affects handlebars |
| GHSA-xhpv-hc6g-r9c6 Handlebars.js has JavaScript Injection via AST Type Confusion when passing an object as dynamic partial | High | Also affects handlebars |
| GHSA-9cx6-37pm-9jff Handlebars.js has Denial of Service via Malformed Decorator Syntax in Template Compilation | High | Also affects handlebars |
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