Improper Restriction of Rendered UI Layers or Frames in yourls/yourls

published 2021-08-26 5 y ago modified 2026-06-17 4 mo ago also GHSA-r6g8-jmj9-g945 , EUVD-2021-1859

cvss: 6.5; version 3.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 35%
public exploits: 0; none known

yourls is vulnerable to Improper Restriction of Rendered UI Layers or Frames

Patch / fix

links 1

github.com/yourls/yourls@0a70acd commit

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-3734 updated 2025-11-21 cvss 6.5

yourls: Improper Restriction of Rendered UI Layers or Frames

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

huntr.dev https://huntr.dev/bounties/dd2e2dbe-efe5-49ec-be11-7a7e7c41debd referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.0	6.5	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
NVD	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD	2.0	6.8	AV:N/AC:M/Au:N/C:P/I:P/A:P
GitHub	3.0	6.5	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
packagist	yourls/yourls	<=1.8.1	no fix listed

Affected products

yourls yourls/yourls

Classification

Weakness

CWE-1021 Improper Restriction of Rendered UI Layers or Frames
CWE-352 Cross-Site Request Forgery

References

github.com /yourls/yourls/commit/0a70acdcfb5fcbc63dbc5750018d608288eba3fe
web, patch, third-party-advisory
huntr.dev /bounties/dd2e2dbe-efe5-49ec-be11-7a7e7c41debd
web, exploit, issue-tracking, third-party-advisory
nvd.nist.gov /vuln/detail/CVE-2021-3734
advisory
github.com /yourls/yourls
package

Sources

CVE List CVE-2021-3734
GitHub Advisory GHSA-r6g8-jmj9-g945
NVD CVE-2021-3734

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