How severe is CVE-2021-46875?

No CVSS score has been assigned to CVE-2021-46875 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2021-46875?

CVE-2021-46875 affects the following packages: ezsystems/ezpublish-kernel (Packagist), ezsystems/ezpublish-kernel (Packagist), ezsystems/ezplatform-kernel (Packagist), ezsystems/ezplatform-kernel (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2021-46875?

Update ezsystems/ezpublish-kernel to 6.13.8.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-46875 is resolved across your whole dependency graph.

How do I detect CVE-2021-46875 in my Packagist dependencies?

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

How do I mitigate CVE-2021-46875 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 CVE-2021-46875 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-46875 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.

What is the EPSS score for CVE-2021-46875?

CVE-2021-46875 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 32th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-46875?

CVE-2021-46875 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2021-46875 published, and has it been updated?

CVE-2021-46875 was published on March 19, 2021 and was last updated on May 4, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

CVE-2021-46875 — ezpublish-kernel

Fix: ezsystems/ezpublish-kernel@29fecd2

CVE-2021-46875 is a Cross-site Scripting (XSS) vulnerability in ezsystems/ezpublish-kernel. A fix is available for ezsystems/ezpublish-kernel — see the affected versions and patch details below.

Cross-site scripting in eZ Platform Kernel

Published

Mar 19, 2021

Updated

May 4, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

None indexed

Exploitation data as of Oct 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2021-46875.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs32th percentile — riskier than 32% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

4 pkgs affected

🐘ezsystems/ezpublish-kernel🐘ezsystems/ezpublish-kernel🐘ezsystems/ezplatform-kernel🐘ezsystems/ezplatform-kernel

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

Description

Impact

In file upload it is possible by certain means to upload files like .html and .js. These may contain XSS exploits which will be run when links to them are accessed by victims.

Patches

The fix consists simply of adding common types of scriptable file types to the configuration of the already existing filetype blacklist feature. See "Patched versions". As such, this can also be done manually, without installing the patched versions. This may be relevant if you are currently running a considerably older version of the kernel package and don't want to upgrade it at this time. Please see the settting "ezsettings.default.io.file_storage.file_type_blacklist" at: https://github.com/ezsystems/ezplatform-kernel/blob/master/eZ/Bundle/EzPublishCoreBundle/Resources/config/default_settings.yml#L109

Important note

You should adapt this setting to your needs. Do not add file types to the blacklist that you actually need to be able to upload. For instance, if you need your editors to be able to upload SVG files, then don't blacklist that. Instead, you could e.g. use an approval workflow for such content.

Affected Packages

4 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`ezsystems/ezpublish-kernel`	all versions	6.13.8.2`composer require ezsystems/ezpublish-kernel:^6.13.8.2`
🐘Packagist	`ezsystems/ezpublish-kernel`	≥ 7.0.0&&< 7.5.15.2	7.5.15.2`composer require ezsystems/ezpublish-kernel:^7.5.15.2`
🐘Packagist	`ezsystems/ezplatform-kernel`	all versions	1.2.5.1`composer require ezsystems/ezplatform-kernel:^1.2.5.1`
🐘Packagist	`ezsystems/ezplatform-kernel`	≥ 1.3.0&&< 1.3.1.1	1.3.1.1`composer require ezsystems/ezplatform-kernel:^1.3.1.1`

Affected Products

1 product · 4 configurations

ez platform kernelibexa

≥ 7.5.0 && < 7.5.15.2

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ezsystems/ezpublish-kernel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ezsystems/ezpublish-kernel to 6.13.8.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-46875 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

### Impact In file upload it is possible by certain means to upload files like .html and .js. These may contain XSS exploits which will be run when links to them are accessed by victims. ### Patches The fix consists simply of adding common types of scriptable file types to the configuration of the already existing filetype blacklist feature. See "Patched versions". As such, this can also be done manually, without installing the patched versions. This may be relevant if you are currently running a considerably older version of the kernel package and don't want to upgrade it at this time. Pleas

O3 Security · Impact-Aware SCA

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