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Vulnerability details: VCID-7j67-9wrp-ebb2
Vulnerability ID VCID-7j67-9wrp-ebb2
Aliases CVE-2021-26539
GHSA-rjqq-98f6-6j3r
Summary 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.
Status Published
Exploitability 0.5
Weighted Severity 6.2
Risk 3.1
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-20 Improper Input Validation
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
cvssv3 5.3 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-26539.json
cvssv3.1 5.3 https://advisory.checkmarx.net/advisory/CX-2021-4308
generic_textual MODERATE https://advisory.checkmarx.net/advisory/CX-2021-4308
epss 0.00288 https://api.first.org/data/v1/epss?cve=CVE-2021-26539
epss 0.00288 https://api.first.org/data/v1/epss?cve=CVE-2021-26539
epss 0.00288 https://api.first.org/data/v1/epss?cve=CVE-2021-26539
epss 0.00288 https://api.first.org/data/v1/epss?cve=CVE-2021-26539
cvssv3.1_qr MODERATE https://github.com/advisories/GHSA-rjqq-98f6-6j3r
cvssv3.1 5.3 https://github.com/apostrophecms/sanitize-html
generic_textual MODERATE https://github.com/apostrophecms/sanitize-html
cvssv3.1 5.3 https://github.com/apostrophecms/sanitize-html/blob/main/CHANGELOG.md#231-2021-01-22
generic_textual MODERATE https://github.com/apostrophecms/sanitize-html/blob/main/CHANGELOG.md#231-2021-01-22
cvssv3.1 5.3 https://github.com/apostrophecms/sanitize-html/commit/bdf7836ef8f0e5b21f9a1aab0623ae8fcd09c1da
generic_textual MODERATE https://github.com/apostrophecms/sanitize-html/commit/bdf7836ef8f0e5b21f9a1aab0623ae8fcd09c1da
cvssv3.1 5.3 https://github.com/apostrophecms/sanitize-html/pull/458
generic_textual MODERATE https://github.com/apostrophecms/sanitize-html/pull/458
cvssv3.1 5.3 https://nvd.nist.gov/vuln/detail/CVE-2021-26539
generic_textual MODERATE https://nvd.nist.gov/vuln/detail/CVE-2021-26539
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-26539.json
https://advisory.checkmarx.net/advisory/CX-2021-4308
https://api.first.org/data/v1/epss?cve=CVE-2021-26539
https://github.com/apostrophecms/sanitize-html
https://github.com/apostrophecms/sanitize-html/blob/main/CHANGELOG.md#231-2021-01-22
https://github.com/apostrophecms/sanitize-html/commit/bdf7836ef8f0e5b21f9a1aab0623ae8fcd09c1da
https://github.com/apostrophecms/sanitize-html/pull/458
https://nvd.nist.gov/vuln/detail/CVE-2021-26539
1932362 https://bugzilla.redhat.com/show_bug.cgi?id=1932362
GHSA-rjqq-98f6-6j3r https://github.com/advisories/GHSA-rjqq-98f6-6j3r
RHSA-2020:5633 https://access.redhat.com/errata/RHSA-2020:5633
RHSA-2021:2438 https://access.redhat.com/errata/RHSA-2021:2438
RHSA-2021:3759 https://access.redhat.com/errata/RHSA-2021:3759
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-26539.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://advisory.checkmarx.net/advisory/CX-2021-4308
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://github.com/apostrophecms/sanitize-html
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://github.com/apostrophecms/sanitize-html/blob/main/CHANGELOG.md#231-2021-01-22
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://github.com/apostrophecms/sanitize-html/commit/bdf7836ef8f0e5b21f9a1aab0623ae8fcd09c1da
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://github.com/apostrophecms/sanitize-html/pull/458
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-26539
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.5265
EPSS Score 0.00288
Published At June 11, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-06-11T21:11:02.056886+00:00 Debian Importer Import https://security-tracker.debian.org/tracker/data/json 38.6.0