CVE-2021-27516: URI.js (aka urijs) before 1.19.6 mishandles certain uses of backslash such as http:\/ and interprets the URI a

Q: How do I fix CVE-2021-27516?

uri.js: upgrade to 1.19.6. Exact commands for each OS are on this page.

Q: Is CVE-2021-27516 being exploited?

CVE-2021-27516 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-27516 affect?

CVE-2021-27516 affects uri.js. Severity is high (CVSS 7.5). URI.js (aka urijs) before 1.19.6 mishandles certain uses of backslash such as http:\/ and interprets the URI as a relative path.

Q: How urgent is CVE-2021-27516?

Priority 57/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 7.5REMOTEUPGRADE

CVE-2021-27516 is a high-severity flaw (CVSS 7.5) affecting uri.js. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

URI.js (aka urijs) before 1.19.6 mishandles certain uses of backslash such as http:\/ and interprets the URI as a relative path.

Why this priority

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

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.5% (top 15%)
CISA exploited list	No
Published	2021-02-22
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: uri.js project

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

Am I affected?

Timeline

2021-02-22 00:15 UTCPublished CVE record published
2026-06-17 03:45 UTCUpdated Record last modified

uri.js project uri.js UPGRADE

Affected: < 1.19.6

Fixed in: 1.19.6

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy uri.js || rpm -q uri.js || uri.js --version

2. UPGRADE to 1.19.6 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade uri.js

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade uri.js

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2021-27516?

uri.js: upgrade to 1.19.6. Exact commands for each OS are on this page.

Is CVE-2021-27516 being exploited?

CVE-2021-27516 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-2021-27516 affect?

CVE-2021-27516 affects uri.js. Severity is high (CVSS 7.5). URI.js (aka urijs) before 1.19.6 mishandles certain uses of backslash such as http:\/ and interprets the URI as a relative path.

How urgent is CVE-2021-27516?

Priority 57/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2022-24723 MEDIUM 5.3 UPGRADE URI.js is a Javascript URL mutation library
CVE-2022-1243 MEDIUM 6.1 UPGRADE CRHTLF can lead to invalid protocol extraction potentially leading to XSS in GitHub repository medialize/uri.j
CVE-2022-1233 MEDIUM 6.1 UPGRADE URL Confusion When Scheme Not Supplied in GitHub repository medialize/uri.js prior to 1.19.11.
CVE-2022-0868 MEDIUM 6.1 UPGRADE Open Redirect in GitHub repository medialize/uri.js prior to 1.19.10.
CVE-2022-0613 MEDIUM 6.5 UPGRADE MITIGATE Authorization Bypass Through User-Controlled Key in NPM urijs prior to 1.19.8.

References

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