How severe is GHSA-w4vp-3mq7-7v82?

No CVSS score has been assigned to GHSA-w4vp-3mq7-7v82 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-w4vp-3mq7-7v82?

GHSA-w4vp-3mq7-7v82 affects the following packages: lazysizes (npm). Ecosystems affected: npm.

How do I fix GHSA-w4vp-3mq7-7v82?

Update lazysizes to 5.2.1-rc1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-w4vp-3mq7-7v82 is resolved across your whole dependency graph.

How do I detect GHSA-w4vp-3mq7-7v82 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for lazysizes, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-w4vp-3mq7-7v82 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is GHSA-w4vp-3mq7-7v82 actively exploited in the wild?

No public exploit code has been indexed for GHSA-w4vp-3mq7-7v82 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-w4vp-3mq7-7v82 published, and has it been updated?

GHSA-w4vp-3mq7-7v82 was published on September 3, 2020 and was last updated on August 31, 2020. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

Not in CISA KEV

Cross-Site Scripting in lazysizesGHSA-w4vp-3mq7-7v82

GHSA-w4vp-3mq7-7v82 is a security vulnerability in lazysizes. A fix is available for lazysizes — see the affected versions and patch details below.

Published

Sep 3, 2020

Updated

Aug 31, 2020

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Aug 31, 2020 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

📦lazysizes

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

Versions of lazysizes prior to 5.2.1-rc1 are vulnerable to Cross-Site Scripting. The video-embed plugin fails to sanitize the following attributes: data-vimeo, data-vimeoparams, data-youtube and data-ytparams. This allows attackers to execute arbitrary JavaScript in a victim's browser if the attacker has control over the vulnerable attributes.

Recommendation

Upgrade to version 5.2.1-rc1 or later.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`lazysizes`	all versions	5.2.1-rc1`npm install lazysizes@5.2.1-rc1`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for lazysizes, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update lazysizes to 5.2.1-rc1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-w4vp-3mq7-7v82 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

Versions of `lazysizes` prior to 5.2.1-rc1 are vulnerable to Cross-Site Scripting. The `video-embed` plugin fails to sanitize the following attributes: data-vimeo, `data-vimeoparams`, `data-youtube` and `data-ytparams`. This allows attackers to execute arbitrary JavaScript in a victim's browser if the attacker has control over the vulnerable attributes. ## Recommendation Upgrade to version 5.2.1-rc1 or later.

O3 Security · Impact-Aware SCA

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