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Medium, CVSS 6.3amended

Processing untrusted theming resources might execute arbitrary code (ACE)

CVE-2021-21316GHSA-3crj-w4f5-gwh4

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (less-openui5 0.10.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
6.3 · CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N
EPSS
  • CVE-2021-21316: 0.99% estimated exploitation activity in the next 30 days; percentile 62.50 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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: 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: Patches We decided to remove the inline JavaScript…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-3crj-w4f5-gwh4

  2. Revision 1 · created ·

    Published from osv record GHSA-3crj-w4f5-gwh4

Agent brief

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# Patch Next advisory brief: CVE-2021-21316

Advisory: Processing untrusted theming resources might execute arbitrary code (ACE)
IDs: CVE-2021-21316, GHSA-3crj-w4f5-gwh4
Record: https://patchnext.com/advisories/cve-2021-21316 (revision 2, source checked 26 Oct 2026, 12:20 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: less-openui5 0.10.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm less-openui5: affected < 0.10.0; fixed in 0.10.0

## Suggested inspection (read-only)
- `npm ls less-openui5 --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on less-openui5.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-3crj-w4f5-gwh4 (OSV record GHSA-3crj-w4f5-gwh4 lists affected ranges: npm less-openui5 >=0 <0.10.0 (fixed))
- Verified: https://github.com/advisories/GHSA-3crj-w4f5-gwh4 (GitHub-reviewed advisory GHSA-3crj-w4f5-gwh4 lists affected ranges: npm less-openui5 >=0 <0.10.0)

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