How severe is CVE-2021-27516?

CVE-2021-27516 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2021-27516 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27516?

CVE-2021-27516 affects Uri.js Project Uri.js. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-27516?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-27516 published?

CVE-2021-27516 was published on 2021-02-22 and last updated on 2026-06-17.

CVE-2021-27516

CVE-2021-27516 is a high-severity vulnerability in Uri.js Project Uri.js with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (83rd percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Uri.js Project Uri.js
Published: 2021-02-22
Last modified: 2026-06-17

Description

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

Frequently asked questions

What is CVE-2021-27516?: 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 severe is CVE-2021-27516?: CVE-2021-27516 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-27516 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27516?: CVE-2021-27516 affects Uri.js Project Uri.js. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-27516?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-27516 published?: CVE-2021-27516 was published on 2021-02-22 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:uri.js_project:uri.js:*:*:*:*:*:*:*:*

More vulnerabilities in Uri.js Project Uri.js

CVE-2022-0613 — Medium (CVSS 6.5): Authorization Bypass Through User-Controlled Key in NPM urijs prior to 1.19.8.
CVE-2020-26291 — Medium (CVSS 6.5): URI.js is a javascript URL mutation library (npm package urijs). In URI.js before version 1.19.4, the hostname can be…
CVE-2022-1243 — Medium (CVSS 6.1): CRHTLF can lead to invalid protocol extraction potentially leading to XSS in GitHub repository medialize/uri.js prior…
CVE-2022-1233 — Medium (CVSS 6.1): URL Confusion When Scheme Not Supplied in GitHub repository medialize/uri.js prior to 1.19.11.
CVE-2022-0868 — Medium (CVSS 6.1): Open Redirect in GitHub repository medialize/uri.js prior to 1.19.10.
CVE-2021-3647 — Medium (CVSS 6.1): URI.js is vulnerable to URL Redirection to Untrusted Site

All CVEs affecting Uri.js Project Uri.js →