How severe is CVE-2026-6257?

CVE-2026-6257 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-6257 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-6257?

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.

Does CVE-2026-6257 have an EU (EUVD) identifier?

Yes. CVE-2026-6257 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23942.

When was CVE-2026-6257 published?

CVE-2026-6257 was published on 2026-04-20 and last updated on 2026-06-17.

CVE-2026-6257

CVE-2026-6257 is a critical-severity vulnerability with a CVSS 3.x base score of 9.1. 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 9.1)
CVSS v4: 9.2
EPSS exploit prediction: 1% (46th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-23942
Weakness: CWE-434
Published: 2026-04-20
Last modified: 2026-06-17

Description

Vvveb CMS v1.0.8.2 contains a remote code execution vulnerability in its media management functionality where a missing return statement in the file rename handler allows authenticated attackers to rename files to blocked extensions .php or .htaccess. Attackers can exploit this logic flaw by first uploading a text file and renaming it to .htaccess to inject Apache directives that register PHP-executable MIME types, then uploading another file and renaming it to .php to execute arbitrary operating system commands as the www-data user.

Frequently asked questions

What is CVE-2026-6257?: Vvveb CMS v1.0.8.2 contains a remote code execution vulnerability in its media management functionality where a missing return statement in the file rename handler allows authenticated attackers to rename files to blocked extensions .php or .htaccess. Attackers can exploit this logic flaw by first uploading a text file and renaming it to .htaccess to inject Apache directives that register PHP-executable MIME types, then uploading another file and renaming it to .php to execute arbitrary operating system commands as the www-data user.
How severe is CVE-2026-6257?: CVE-2026-6257 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-6257 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-6257?: 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.
Does CVE-2026-6257 have an EU (EUVD) identifier?: Yes. CVE-2026-6257 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23942.
When was CVE-2026-6257 published?: CVE-2026-6257 was published on 2026-04-20 and last updated on 2026-06-17.

References

Other CWE-434 (Unrestricted Upload of File with Dangerous Type) vulnerabilities

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CVE-2025-69129 — Critical (CVSS 10.0): Unauthenticated Arbitrary File Upload in WordPress & WooCommerce Scraper Plugin, Import Data from Any Site <= 1.0.7…
CVE-2026-40772 — Critical (CVSS 10.0): Unauthenticated Arbitrary File Upload in GeekyBot <= 1.2.2 versions.
CVE-2026-40412 — Critical (CVSS 10.0): Unrestricted upload of file with dangerous type in Azure Orbital Spatio allows an unauthorized attacker to execute code…

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