What is CVE-2021-27375?

CVE-2021-27375 is a medium-severity vulnerability in Containous Traefik, classified under Improper Restriction of Rendered UI Layers or Frames (Clickjacking). CVSS score: 5.3/10. Published 2021-02-18.

How severe is CVE-2021-27375?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Containous Traefik

CVE-2021-27375

Traefik before 2.4.5 allows the loading of IFRAME elements from other domains.

Published 2021-02-18 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.008 (53.7th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 54th percentile — 53.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Containous Traefik

Weakness classification (CWE)

CWE-1021 — Improper Restriction of Rendered UI Layers or Frames (Clickjacking)

References

github.com/traefik/traefik/pull/7904 (Patch, Third Party Advisory)
github.com/traefik/traefik/releases/tag/v2.4.5 (Release Notes)

Frequently asked questions

What is CVE-2021-27375?: CVE-2021-27375 is a medium-severity vulnerability in Containous Traefik, classified under Improper Restriction of Rendered UI Layers or Frames (Clickjacking). CVSS score: 5.3/10. Published 2021-02-18.
How severe is CVE-2021-27375?: Medium severity. CVSS v3 base score is 5.3 out of 10.