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osvGoogleOSV:GHSA-C78W-2GW7-GJV3
HistoryMay 11, 2020 - 8:00 p.m.

XSS in TinyMCE

2020-05-1120:00:15
Google
osv.dev
8

6.1 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

CHANGED

Confidentiality Impact

LOW

Integrity Impact

LOW

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

4.3 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

PARTIAL

Availability Impact

NONE

AV:N/AC:M/Au:N/C:N/I:P/A:N

0.001 Low

EPSS

Percentile

44.7%

Impact

A cross-site scripting (XSS) vulnerability was discovered in: the core parser and media plugin. The vulnerability allowed arbitrary JavaScript execution when inserting a specially crafted piece of content into the editor via the clipboard or APIs. This impacts all users who are using TinyMCE 4.9.9 or lower and TinyMCE 5.2.1 or lower.

Patches

This vulnerability has been patched in TinyMCE 4.9.10 and 5.2.2 by improved HTML parsing and sanitization logic.

Workarounds

The workarounds available are:

  • disable the media plugin and manually sanitize CDATA content (see below)
    or
  • upgrade to either TinyMCE 4.9.10 or TinyMCE 5.2.2

Example: Manually strip CDATA elements

setup: function(editor) {
  editor.on('PreInit', function() {
    editor.parser.addNodeFilter('#cdata', function(nodes) {
      for (var i = 0; i < nodes.length; i++) {
        nodes[i].remove();
      }
    });
  });
}

Acknowledgements

Tiny Technologies would like to thank MichaΕ‚ Bentkowski and intivesec for discovering these vulnerabilities.

References

https://www.tiny.cloud/docs/release-notes/release-notes522/#securityfixes

For more information

If you have any questions or comments about this advisory:

CPENameOperatorVersion
tinymcelt5.2.2
tinymcege5.0.0
tinymcelt4.9.10

6.1 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

CHANGED

Confidentiality Impact

LOW

Integrity Impact

LOW

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

4.3 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

PARTIAL

Availability Impact

NONE

AV:N/AC:M/Au:N/C:N/I:P/A:N

0.001 Low

EPSS

Percentile

44.7%