CVE-2021-21316Public exploit

Code execution via inline JavaScript in LESS themes

Published Feb 16, 2021 · Updated Aug 3, 2024

Code injection in SAP SE less-openui5 before 0.10.0 allows context-dependent attackers to execute code through a crafted LESS theme. The bundled Less.js 1.6.3 parser treats backtick-delimited expressions in untrusted .less input as JavaScript and evaluates them in the build process. Exploitation requires a developer or automated workflow to build an attacker-supplied library or theme, granting the injected code the build process's access.

CVSS severity6.3
Medium
EPSS probability0.99%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in SAP SE less-openui5 before 0.10.0 allows context-dependent attackers to execute code through a crafted LESS theme. The bundled Less.js 1.6.3 parser treats backtick-delimited expressions in untrusted .less input as JavaScript and evaluates them in the build process. Exploitation requires a developer or automated workflow to build an attacker-supplied library or theme, granting the injected code the build process's access.

The record

CVE
CVE-2021-21316
Published
Feb 16, 2021
Updated
Aug 3, 2024
Vendor
SAP SE
Product
less-openui5
Classifications
CWE-74, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 16, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.10.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

SAP SE · less-openui5version=< 0.10.0

Published CVSS scores

6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
6.3GitHub, Inc.CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
T1204.002User Execution: Malicious File

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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