CVE-2026-77939CWE-1336CWE-94code-injection

CVE-2026-77939

Medium · published August 29, 2026

CVSS v3.1
6.5
EPSS
1%
Percentile
48.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
6.5 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CVSS v4.0
7.1 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
EPSS
0.00610 · 48.6th percentile
Weaknesses
CWE-1336 · Improper Neutralization of Special Elements Used in a Template Engine; CWE-94 · Improper Control of Generation of Code ('Code Injection')
Published
2026-08-29T00:19Z
References (2)
https://github.com/flextype/flextype/issues/595 · [email protected]https://www.vulncheck.com/advisories/flextype-cms-dev-rce-via-post-api-v1-query-endpoint · [email protected]
EPSS history
Timeline
  • 30 AUG 16:19Z
    EPSS moved — → 0%
    epss
  • 28 AUG 17:06Z
    Flextype CMS 1.0.0-dev RCE via POST /api/v1/query Endpoint
    cvelistv5