Regular Expression Denial of Service in negotiator

published 2018-05-31 8 y ago modified 2026-06-17 4 mo ago also GHSA-7mc5-chhp-fmc3 , EUVD-2018-0538

cvss: 7.5; version 3.0, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.4%; EPSS 1.4% chance of exploitation in 30 days, percentile 71%
public exploits: 0; none known

negotiator is an HTTP content negotiator for Node.js and is used by many modules and frameworks including Express and Koa. The header for "Accept-Language", when parsed by negotiator 0.6.0 and earlier is vulnerable to Regular Expression Denial of Service via a specially crafted string.

Patch / fix

fixed in 1 distros 2

npm negotiator 0.6.1

debian ubuntu

node-negotiator Debian 14, Debian 13, Debian 12 0.6.1-1

debian advisories DEBIAN-CVE-2016-10539

node-negotiator Ubuntu 20.04 LTS, Ubuntu 18.04 LTS 0.6.1-1

ubuntu advisories UBUNTU-CVE-2016-10539

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Exploit prediction

1.36% chance of exploitation in the next 30 days, higher than 71% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
NVD	3.0	7.5	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected packages

ecosystem	package	affected	fixed in
npm	negotiator	<0.6.1	0.6.1

Affected products

HackerOne negotiator node module

Classification

Weakness

CWE-400 Uncontrolled Resource Consumption
CWE-20 Improper Input Validation

References

nodesecurity.io /advisories/106
third-party-advisory
nvd.nist.gov /vuln/detail/CVE-2016-10539
advisory
github.com /advisories/GHSA-7mc5-chhp-fmc3
advisory
npmjs.com /advisories/106
web

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary