CVE-2021-21316: less-openui5 is an npm package which enables building OpenUI5 themes with Less.js. In less-openui5 before version 0.10., when processing theming resou...

Description

less-openui5 is an npm package which enables building OpenUI5 themes with Less.js. In less-openui5 before version 0.10., 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. 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. Refer to the referenced GHSA-3crj-w4f5-gwh4 for examples. 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. 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 0.10.0.

Metrics

CVSS 3.1

7.8/10

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

EPSS Probability

0.99%

58.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-74

Affected Software

Vendor	Product	Versions
Less-Openui5 Project	Less-Openui5	< 0.10.0

References

http://lesscss.org/usage/#less-options-enable-inline-javascript-deprecated-Third Party Advisory
https://github.com/SAP/less-openui5/commit/c0d3a8572974a20ea6cee42da11c614a54f100e8Patch, Third Party Advisory
https://github.com/SAP/less-openui5/releases/tag/v0.10.0Release Notes, Third Party Advisory
https://github.com/SAP/less-openui5/security/advisories/GHSA-3crj-w4f5-gwh4Third Party Advisory
https://www.npmjs.com/package/less-openui5Product, Third Party Advisory
http://lesscss.org/usage/#less-options-enable-inline-javascript-deprecated-Third Party Advisory
https://github.com/SAP/less-openui5/commit/c0d3a8572974a20ea6cee42da11c614a54f100e8Patch, Third Party Advisory
https://github.com/SAP/less-openui5/releases/tag/v0.10.0Release Notes, Third Party Advisory
https://github.com/SAP/less-openui5/security/advisories/GHSA-3crj-w4f5-gwh4Third Party Advisory
https://www.npmjs.com/package/less-openui5Product, Third Party Advisory

Timeline

Published: Feb 16, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-21316?

less-openui5 is an npm package which enables building OpenUI5 themes with Less.js. In less-openui5 before version 0.10., 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. 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. Refer to the referenced GHSA-3crj-w4f5-gwh4 for examples. 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. 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 0.10.0.

How severe is CVE-2021-21316?

CVE-2021-21316 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.99% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21316?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.