CVE-2021-27375: Traefik before 2.4.5 allows the loading of IFRAME elements from other domains.

Q: How do I fix CVE-2021-27375?

traefik: upgrade to 2.4.5. Exact commands for each OS are on this page.

Q: Is CVE-2021-27375 being exploited?

CVE-2021-27375 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-27375 affect?

CVE-2021-27375 affects traefik. Severity is medium (CVSS 5.3). Traefik before 2.4.5 allows the loading of IFRAME elements from other domains.

Q: How urgent is CVE-2021-27375?

Priority 37/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2021-27375 is a medium-severity flaw (CVSS 5.3) affecting traefik. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.8% (top 45%)
CISA exploited list	No
Weakness	CWE-1021
Published	2021-02-18
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: containous

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-02-18 03:15 UTCPublished CVE record published
2026-06-17 03:44 UTCUpdated Record last modified

containous traefik UPGRADE

Affected: < 2.4.5

Fixed in: 2.4.5

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy traefik || rpm -q traefik || traefik --version

2. UPGRADE to 2.4.5 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade traefik

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade traefik

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-27375?

traefik: upgrade to 2.4.5. Exact commands for each OS are on this page.

Is CVE-2021-27375 being exploited?

CVE-2021-27375 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-27375 affect?

CVE-2021-27375 affects traefik. Severity is medium (CVSS 5.3). Traefik before 2.4.5 allows the loading of IFRAME elements from other domains.

How urgent is CVE-2021-27375?

Priority 37/100. Remotely exploitable, no login, no user action

Software pages

Traefik vulnerabilities

Related CVEs

CVE-2026-114656 HIGH 7.5 UPGRADE Traefik before 2.11.58 and 3.7.13 contains an authentication bypass vulnerability that allows unauthenticated
CVE-2026-88010 MEDIUM 5.3 UPGRADE Traefik is an open source HTTP reverse proxy and load balancer
CVE-2026-114641 LOW 3.7 UPGRADE Traefik 2.11.x before 2.11.58 and 3.x before 3.7.14 contains a race condition in NTLM and Kerberos (Negotiate)
CVE-2026-114637 HIGH 8.7 UPGRADE Traefik from v3.2.0 before v3.7.14 contains an authentication bypass vulnerability in the experimental FastPro
CVE-2026-114640 HIGH 8.7 UPGRADE Traefik from v3.7.0 before v3.7.14 contains an authentication bypass vulnerability in its Kubernetes Ingress-N

References

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