How severe is CVE-2026-39918?

CVE-2026-39918 has a CVSS 3.x base score of 9.8, 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-2026-39918 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-39918?

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-2026-39918 have an EU (EUVD) identifier?

Yes. CVE-2026-39918 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23868.

When was CVE-2026-39918 published?

CVE-2026-39918 was published on 2026-04-20 and last updated on 2026-06-17.

CVE-2026-39918

CVE-2026-39918 is a critical-severity vulnerability with a CVSS 3.x base score of 9.8. 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-94.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v4: 9.2
EPSS exploit prediction: 1% (47th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-23868
Weakness: CWE-94
Published: 2026-04-20
Last modified: 2026-06-17

Description

Vvveb prior to 1.0.8.1 contains a code injection vulnerability in the installation endpoint where the subdir POST parameter is written unsanitized into the env.php configuration file without escaping or validation. Attackers can inject arbitrary PHP code by breaking out of the string context in the define statement to achieve unauthenticated remote code execution as the web server user.

Frequently asked questions

What is CVE-2026-39918?: Vvveb prior to 1.0.8.1 contains a code injection vulnerability in the installation endpoint where the subdir POST parameter is written unsanitized into the env.php configuration file without escaping or validation. Attackers can inject arbitrary PHP code by breaking out of the string context in the define statement to achieve unauthenticated remote code execution as the web server user.
How severe is CVE-2026-39918?: CVE-2026-39918 has a CVSS 3.x base score of 9.8, 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-2026-39918 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-39918?: 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-2026-39918 have an EU (EUVD) identifier?: Yes. CVE-2026-39918 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23868.
When was CVE-2026-39918 published?: CVE-2026-39918 was published on 2026-04-20 and last updated on 2026-06-17.

References

Other CWE-94 (Code Injection) vulnerabilities

CVE-2026-57624 — Critical (CVSS 10.0): Unauthenticated Remote Code Execution (RCE) in Blocksy Companion Pro <= 2.1.46 versions.
CVE-2026-10134 — Critical (CVSS 10.0): IBM Langflow OSS 1.0.0 through 1.9.3 allows an attacker to read every secret available to the Langflow process, read…
CVE-2026-53576 — Critical (CVSS 10.0): Kestra is an open-source, event-driven orchestration platform. Prior to 1.0.45 and 1.3.21, the authentication filter…
CVE-2026-10561 — Critical (CVSS 10.0): IBM Langflow OSS 1.0.0 through 1.9.3 has an vulnerability due to an improper isolation of Python execution combined…
CVE-2026-25470 — Critical (CVSS 10.0): Improper Control of Generation of Code ('Code Injection') vulnerability in ACPT ACPT (Pro) - Custom Post Types Plugin…
CVE-2026-48836 — Critical (CVSS 10.0): Unauthenticated Remote Code Execution (RCE) in Easy Invoice <= 2.1.19 versions.

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