CVE-2021-26540

MEDIUM
Published Feb 8, 20215y ago · Modified Jun 17, 20262w ago
5.3 CVSS 3.1
Medium
Find Similar
Published Feb 8, 2021 5y ago
Last Modified Jun 17, 2026 2w ago

Description

Apostrophe Technologies sanitize-html before 2.3.2 does not properly validate the hostnames set by the "allowedIframeHostnames" option when the "allowIframeRelativeUrls" is set to true, which allows attackers to bypass hostname whitelist for iframe element, related using an src value that starts with "/\\example.com".

CVSS Details

Base Score
5.3
Exploitability
3.9
Impact
1.4
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity Low
Availability None

Threat Intelligence

No active exploitation signals — not in CISA KEV and no EPSS score yet.

Exploit & Patch Status
Public Exploit Known
Patch Available

Affected Products 1

VendorProductVersionRange
apostrophecmssanitize-html* <2.3.2

References 3

  • advisory.checkmarx.net https://advisory.checkmarx.net/advisory/CX-2021-4309
    ExploitPatchThird Party Advisory
  • github.com https://github.com/apostrophecms/sanitize-html/blob/main/CHANGELOG.md#232-2021-01-26
    Release NotesThird Party Advisory
  • github.com https://github.com/apostrophecms/sanitize-html/pull/460
    PatchThird Party Advisory

Remediation

  • advisory.checkmarx.net https://advisory.checkmarx.net/advisory/CX-2021-4309
    ExploitPatchThird Party Advisory
  • github.com https://github.com/apostrophecms/sanitize-html/pull/460
    PatchThird Party Advisory