CVE-2016-10539: Regular Expression Denial of Service in negotiator
Summary
CVE-2016-10539: Regular Expression Denial of Service in negotiator. Affects negotiator versions < 0.6.1. Fixed in 0.6.1. How to fix ↓
Also tracked for
- node-negotiator · Debian:11
The same CVE-2016-10539 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
The negotiator package is an npm package used for parsing and negotiating HTTP headers. It is commonly used in web applications to determine the preferred language, encoding, and other header values. The package provides a simple and efficient way to handle header negotiation. However, versions prior to 0.6.1 are vulnerable to a regular expression denial of service (ReDoS) attack when parsing a specially crafted Accept-Language header value.
Vulnerability Detail
The vulnerability in negotiator arises from a regular expression used to parse the Accept-Language header value. An attacker can send a malicious Accept-Language header with a specially crafted value that triggers a ReDoS attack. This attack can cause the parsing process to consume excessive CPU resources, leading to a denial of service condition. The impact of this vulnerability can range from degraded performance to a complete system outage.
How To Fix
Latest published version: 1.1.0 as of 22 Oct 2026
npm install negotiator@1.1.0Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
0.6.1
This is the first release that contains the fix.
npm install negotiator@0.6.1Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
There is no known workaround for this vulnerability. It is essential to update to the fixed version of the negotiator package to mitigate the risk of a regular expression denial of service attack.
Conclusion
The negotiator package prior to version 0.6.1 is vulnerable to a regular expression denial of service attack. To mitigate this vulnerability, it is recommended to update to the latest version of the package. For further support on vulnerability remediation, contact DevNack.com.
See every vulnerability recorded for negotiator →
FAQ
negotiator is an npm package used for parsing and negotiating HTTP headers. It is commonly used in web applications to determine the preferred language, encoding, and other header values.
A regular expression denial of service (ReDoS) attack is a type of denial of service attack that exploits the way certain regular expressions are processed. By providing a specially crafted input, an attacker can cause the regular expression matching algorithm to take an excessive amount of time, leading to a denial of service condition.
The impact of this vulnerability can range from degraded performance to a complete system outage. If an attacker successfully triggers a ReDoS attack, the parsing process of the Accept-Language header can consume excessive CPU resources, causing the application to become unresponsive or crash.
To fix this vulnerability, update the negotiator package to version 0.6.1 or later. This version includes a fix for the regular expression denial of service vulnerability. Updating the package ensures that the vulnerable code is replaced with a secure implementation.
There is no known workaround for this vulnerability. It is crucial to update to the fixed version of the negotiator package to mitigate the risk of a regular expression denial of service attack.
