What is CVE-2021-3785?

CVE-2021-3785 is a medium-severity vulnerability in Yourls, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-09-15.

How severe is CVE-2021-3785?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Yourls

CVE-2021-3785

yourls is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-09-15 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.007 (52.1th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 52.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Yourls
Yourls Yourls/yourls — versions unspecified

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

huntr.dev/bounties/b4085d13-54fa-4419-a2ce-1d780cc31638 (Exploit, Patch, Third Party Advisory, Issue Tracking)
github.com/yourls/yourls/commit/1d8e224ebabb8a4c75b97f026950ed710faab0ff (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-3785?: CVE-2021-3785 is a medium-severity vulnerability in Yourls, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-09-15.
How severe is CVE-2021-3785?: Medium severity. CVSS v3 base score is 5.4 out of 10.