Ecosyste.ms: Advisories

Security Advisories: MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTNjcmotdzRmNS1nd2g0

Processing untrusted theming resources might execute arbitrary code (ACE)

Impact

When processing theming resources (i.e. *.less files) with less-openui5 that originate from an untrusted source, those resources might contain JavaScript code which will be executed in the context of the build process.

While this is a feature of the Less.js library, it is an unexpected behavior in the context of OpenUI5 and SAPUI5 development.

Especially in the context of UI5 Tooling, which relies on less-openui5, this poses a security threat:

An attacker might create a library or theme-library containing a custom control or theme, hiding malicious JavaScript code in one of the .less files.

This is an example of inline JavaScript in a Less file:

.rule {
	@var: `(function(){console.log('Hello from JavaScript'); process.exit(1);})()`;
	color: @var;
}

Starting with Less.js version 3.0.0, the Inline JavaScript feature is disabled by default. less-openui5 however currently uses a fork of Less.js v1.6.3.

Note that disabling the Inline JavaScript feature in Less.js versions 1.x, still evaluates code has additional double codes around it:

.rule {
	@var: "`(function(){console.log('Hello from JavaScript'); process.exit(1);})()`";
	color: @var;
}

Patches

We decided to remove the inline JavaScript evaluation feature completely from the code of our Less.js fork.

This fix is available in less-openui5 version v0.10.0

Workarounds

Only process trusted theming resources.

For more information

If you have any questions or comments about this advisory:

• Open an issue in https://github.com/SAP/less-openui5
• Email us at [email protected]

Permalink: https://github.com/advisories/GHSA-3crj-w4f5-gwh4
JSON: https://advisories.ecosyste.ms/api/v1/advisories/MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTNjcmotdzRmNS1nd2g0
Source: GitHub Advisory Database
Origin: Unspecified
Severity: High
Classification: General
Published: over 3 years ago
Updated: over 1 year ago

CVSS Score: 6.3
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N

Identifiers: GHSA-3crj-w4f5-gwh4, CVE-2021-21316
References:

• https://github.com/SAP/less-openui5/security/advisories/GHSA-3crj-w4f5-gwh4
• https://github.com/SAP/less-openui5/commit/c0d3a8572974a20ea6cee42da11c614a54f100e8
• https://www.npmjs.com/package/less-openui5
• https://github.com/SAP/less-openui5/releases/tag/v0.10.0
• http://lesscss.org/usage/#less-options-enable-inline-javascript-deprecated-
• https://nvd.nist.gov/vuln/detail/CVE-2021-21316
• https://github.com/advisories/GHSA-3crj-w4f5-gwh4

Repository: https://github.com/SAP/less-openui5
Blast Radius: 19.9

Affected Packages