CVE-2026-39387: Boidcms remote code execution (CVSS 7.2)

Description

BoidCMS is an open-source, PHP-based flat-file CMS for building simple websites and blogs, using JSON as its database. Versions prior to 2.1.3 are vulnerable to a critical Local File Inclusion (LFI) attack via the tpl parameter, which can lead to Remote Code Execution (RCE).The application fails to sanitize the tpl (template) parameter during page creation and updates. This parameter is passed directly to a require_once() statement without path validation. An authenticated administrator can exploit this by injecting path traversal sequences (../) into the tpl value to escape the intended theme directory and include arbitrary files — specifically, files from the server's media/ directory. When combined with the file upload functionality, this becomes a full RCE chain: an attacker can first upload a file with embedded PHP code (e.g., disguised as image data), then use the path traversal vulnerability to include that file via require_once(), executing the embedded code with web server privileges. This issue has been fixed in version 2.1.3.

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredHigh

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Affected products

Boidcms< 2.1.3

Remediation

Fixed in

Boidcms≥ 2.1.3

Patch & vendor advisories

https://github.com/BoidCMS/BoidCMS/security/advisories/GHSA-45xp-xw54-6cv6

References

https://github.com/BoidCMS/BoidCMS/releases/tag/v2.1.3ProductRelease Notes
https://github.com/BoidCMS/BoidCMS/security/advisories/GHSA-45xp-xw54-6cv6ExploitMitigationVendor Advisory

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-39387 being actively exploited?

CVE-2026-39387 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.81%.

How severe is CVE-2026-39387?

CVE-2026-39387 has a CVSS 3.1 base score of 7.2, rated high. EPSS estimates a 0.81% probability of exploitation.

Which products are affected by CVE-2026-39387?

Affected products include Boidcms.

How do I fix CVE-2026-39387?

Upgrade affected software to a fixed version, for example Boidcms 2.1.3 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-39387 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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