What is CVE-2026-77939?

CVE-2026-77939 is a medium-severity vulnerability in Flextype, classified under Code Injection. CVSS score: 6.5/10. Published 2026-08-28.

How severe is CVE-2026-77939?

Medium severity. CVSS v3 base score is 6.5 out of 10.

RCE in Flextype

CVE-2026-77939

Flextype CMS through v1.0.0-dev contains an expression language injection vulnerability that allows authenticated attackers with a valid API token to read arbitrary files by passing unsanitized user-supplied input to the Symfony ExpressionLanguage engine via the POST /api/v1/query endpoint. Attackers can leverage exposed application objects including filesystem() and serializers() within the evaluation scope to read arbitrary server files and achieve conditional remote code execution if a PHP file can be placed on disk through a secondary vector.

Vulnerability class: RCE (Remote Code Execution)

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

Affected products

Flextype

Weakness classification (CWE)

References

disclosure@vulncheck.com (technical-description, exploit)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-77939?: CVE-2026-77939 is a medium-severity vulnerability in Flextype, classified under Code Injection. CVSS score: 6.5/10. Published 2026-08-28.
How severe is CVE-2026-77939?: Medium severity. CVSS v3 base score is 6.5 out of 10.