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CVE-2021-27516

25
FAUCET Score

CVE-2021-27516 describes a vulnerability in URI.js (aka urijs) versions prior to 1.19.6, where the library incorrectly parses URIs containing backslashes, such as "http:\/", interpreting them as relative paths instead of absolute ones. This high-severity vulnerability (CVSS 7.5) has a low attack complexity and requires no user interaction, potentially leading to high confidentiality impacts. Despite its severity, there is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.19.6CPE matchmatch criteria
cpe:2.3:a:uri.js_project:uri.js:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.48%
Probability of exploitation in next 30 days
EPSS Percentile
82.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0248 is in the 70th percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

github_advisorypatch availablevia nvd_reference
View patch
npmpatch availablevia ghsa
Product: urijsFixed in: 1.19.6
redhatpatch availablevia redhat_api
Product: Red Hat Quay 3Fixed in: quay/quay-rhel8:v3.6.0-62
View patch

Vendor Advisories (2)

npmGHSA-p6j9-7xhc-rhwphigh

URIjs Hostname spoofing via backslashes in URL

Mar 1, 2021
redhatCVE-2021-27516Important

nodejs-urijs: mishandling certain uses of backslash may lead to confidentiality compromise

Feb 22, 2021

References

advisory.checkmarx.net / advisory/CX-2021-4305
ExploitThird Party Advisory
github.com / medialize/URI.js/commit/a1ad8bcbc39a4d136d7e252e76e957f3ece70839
PatchThird Party Advisory
github.com / medialize/URI.js/releases/tag/v1.19.6
Third Party Advisory