CVE-2026-25099

High

Published: 27 March 2026

Published

27 March 2026

Modified

01 April 2026

KEV Added

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Patch

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CVSS Score 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Score 0.0142 80.8th percentile

Risk Priority 18 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-25099 is a high-severity Unrestricted Upload of File with Dangerous Type (CWE-434) vulnerability in Bludit Bludit. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 19.2% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 1 other technique. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-10 Information Input Validation good match

prevent

Requires validation of file types and extensions at the API upload endpoint, directly preventing unrestricted uploads of dangerous files leading to RCE.

SI-2 Flaw Remediation good match

prevent

Mandates timely remediation of identified flaws, such as patching Bludit to version 3.18.4 to fix the API plugin's upload vulnerability.

SI-9 Information Input Restrictions good match

prevent

Enforces restrictions on allowed file types at API input points, blocking uploads of executable or dangerous extensions exploited in this CVE.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1505.003 Web Shell Persistence

Adversaries may backdoor web servers with web shells to establish persistent access to systems.

attack.mitre.org →

Why these techniques?

CVE enables exploitation of public-facing CMS API (T1190) through unrestricted file uploads, directly facilitating web shell deployment and RCE (T1100).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

NVD Description

Bludit’s API plugin allows an authenticated attacker with a valid API token to upload files of any type and extension without restriction, which can then be executed, leading to Remote Code Execution. This issue was fixed in 3.18.4.

Deeper analysisAI

CVE-2026-25099 is a high-severity vulnerability in Bludit, an open-source flat-file CMS, specifically affecting its API plugin. The flaw allows unrestricted file uploads of any type and extension, enabling subsequent execution of uploaded files and resulting in remote code execution (RCE). Assigned CWE-434 (Unrestricted Upload of File with Dangerous Type), it carries a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H), highlighting its critical impact due to network accessibility, low attack complexity, and low privilege requirements.

An authenticated attacker possessing a valid API token can exploit this vulnerability remotely without user interaction. By leveraging the API plugin's lack of file type or extension restrictions, the attacker uploads malicious files—such as web shells—that can then be executed on the server, granting full control over the affected Bludit instance, including data exfiltration, persistence, or further lateral movement.

Mitigation is available through the official patch in Bludit version 3.18.4, as detailed in the release notes on GitHub. Additional advisory information from CERT.pl outlines the issue and recommends immediate upgrading to the fixed version, along with reviewing API token access controls to limit exposure.