Cross-site Scripting (XSS) - Stored in yourls/yourls

published 2021-09-15 5 y ago modified 2026-06-17 4 mo ago also GHSA-m9fq-c9hp-59g7 , EUVD-2021-2092

cvss: 8.8; version 3.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.7%; EPSS 0.7% chance of exploitation in 30 days, percentile 54%
public exploits: 0; none known

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

Patch / fix

fixed in 2 links 2

packagist yourls/yourls 1.8.2
yourls yourls/yourls 1.8.2

github.com/yourls/yourls@1d8e224 commit
huntr.dev/bounties/b4085d13-54fa-4419-a2ce-1d780cc31638 advisory

Exploit prediction

0.72% chance of exploitation in the next 30 days, higher than 54% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

huntr.dev https://huntr.dev/bounties/b4085d13-54fa-4419-a2ce-1d780cc31638 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.0	8.8	CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
NVD	2.0	3.5	AV:N/AC:M/Au:S/C:N/I:P/A:N
GitHub	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
packagist	yourls/yourls	<1.8.2	1.8.2

Affected products

yourls yourls/yourls

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

github.com /yourls/yourls/commit/1d8e224ebabb8a4c75b97f026950ed710faab0ff
web, patch, third-party-advisory
huntr.dev /bounties/b4085d13-54fa-4419-a2ce-1d780cc31638
web, exploit, issue-tracking, patch, third-party-advisory
nvd.nist.gov /vuln/detail/CVE-2021-3785
advisory
github.com /yourls/yourls
package

Sources

CVE List CVE-2021-3785
GitHub Advisory GHSA-m9fq-c9hp-59g7
NVD CVE-2021-3785

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary