How severe is CVE-2026-4357?

CVE-2026-4357 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-4357 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-4357?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2026-4357 published?

CVE-2026-4357 was published on 2026-09-02 and last updated on 2026-09-03.

CVE-2026-4357

CVE-2026-4357 is a critical-severity vulnerability with a CVSS 3.x base score of 10.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-434.

Key facts

Severity: Critical (CVSS 3.x base score 10.0)
EPSS exploit prediction: 0% (23rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-434
Published: 2026-09-02
Last modified: 2026-09-03

Description

The Embed HTML5 Game WordPress plugin through 1.3 does not properly restrict who can upload files via the plugin, as well as what can be uploaded, making it possible for unauthenticated attackers to upload PHP backdoors on affected sites.

Frequently asked questions

What is CVE-2026-4357?: The Embed HTML5 Game WordPress plugin through 1.3 does not properly restrict who can upload files via the plugin, as well as what can be uploaded, making it possible for unauthenticated attackers to upload PHP backdoors on affected sites.
How severe is CVE-2026-4357?: CVE-2026-4357 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-4357 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-4357?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-4357 published?: CVE-2026-4357 was published on 2026-09-02 and last updated on 2026-09-03.

References

https://wpscan.com/vulnerability/b364969d-9dac-46ce-83e2-fc0fc2e5f698/

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