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TinyMCE allows svg files linked in object tags

Moderate
emteknetnz published GHSA-52cw-pvq9-9m5v Jul 17, 2024

Package

composer silverstripe/framework (Composer)

Affected versions

< 5.2.16

Patched versions

5.2.16

Description

Impact

TinyMCE v6 has a configuration value convert_unsafe_embeds set to false which allows svg files containing javascript to be used in <object> or <embed> tags, which can be used as a vector for XSS attacks.

Note that <embed> tags are not allowed by default.

After patching the default value of convert_unsafe_embeds will be set to true. This means that <object> tags will be converted to iframes instead the next time the page is saved, which may break any pages that rely upon previously saved <object> tags. Developers can override this configuration if desired to revert to the original behaviour.

We reviewed the potential impact of this vulnerability within the context of Silverstripe CMS. We concluded this is a medium impact vulnerability given how TinyMCE is used by Silverstripe CMS.

References:

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

CVE ID

No known CVE

Weaknesses

No CWEs