GHSA-3crj-w4f5-gwh4 Processing untrusted theming resources might execute arbitrary code (ACE)

• npm less-openui5: < 0.10.0 → fixed in 0.10.0

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: ```less .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: ```less .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]