MEDIUM

CVE-2021-26539

CVSS v3

5.3

MEDIUM

EPSS Score

2.0 %

exploit probability, as of 2026-10-19

CISA KEV

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

sanitize-htmlnpmall versions · fixed in 2.3.1

Vendor advisories

CVE-2021-26539 Red Hat Product Security10 products fixed · 2 known affected
sanitize-html: improper handling of internationalized domain name (IDN) can lead to bypass hostname whitelist validation
servicemesh-prometheus as a component of OpenShift Service Mesh 2.0 · servicemesh-prometheus.src as a component of OpenShift Service Mesh 2.0
RHSA-2021:3759 Red Hat Product Security4 products fixed
Red Hat Security Advisory: OpenShift Container Platform 4.9.0 bug fix and security update
RHSA-2021:2438 Red Hat Product Security3 products fixed
Red Hat Security Advisory: OpenShift Container Platform 4.8.2 bug fix and security update

Full record on NVD

Description

Apostrophe Technologies sanitize-html before 2.3.1 does not properly handle internationalized domain name (IDN) which could allow an attacker to bypass hostname whitelist validation set by the "allowedIframeHostnames" option.

Technical details

Published: 2021-02-08

Frequently asked questions

What is CVE-2021-26539?

Is CVE-2021-26539 actively exploited?

Active exploitation of CVE-2021-26539 has not been confirmed. Its EPSS score was 2.0% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-26539?

CVE-2021-26539 has a CVSS v3 base score of 5.3 (MEDIUM severity).

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