CVE-2020-26311: Useragent is a user agent parser for Node.js

This week

HIGH 7.5REMOTEMITIGATE

CVE-2020-26311 is a high-severity flaw (CVSS 7.5) affecting useragent. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Useragent is a user agent parser for Node.js. All versions as of time of publication contain one or more regular expressions that are vulnerable to Regular Expression Denial of Service (ReDoS). As of time of publication, no patches are available.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 56%)
CISA exploited list	No
Weakness	CWE-1333
Published	2024-10-26
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: useragent project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2024-10-26 21:15 UTCPublished CVE record published
2026-06-17 03:08 UTCUpdated Record last modified

useragent project useragent MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

npm ls useragent

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-26311?

useragent: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-26311 being exploited?

CVE-2020-26311 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-26311 affect?

CVE-2020-26311 affects useragent. Severity is high (CVSS 7.5). Useragent is a user agent parser for Node.js. All versions as of time of publication contain one or more regular expressions that are vulnerable to Regular Expression Denial of Service (ReDoS). As of time of publication, no patches are avai

How urgent is CVE-2020-26311?

Priority 47/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Node.js vulnerabilities

References

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