CVE-2026-21625
Published: 16 January 2026
Summary
CVE-2026-21625 is a medium-severity Unrestricted Upload of File with Dangerous Type (CWE-434) vulnerability in Stackideas Easydiscuss. Its CVSS base score is 4.8 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 26.4th percentile by exploit likelihood (below the median); 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).
Deeper analysis
CVE-2026-21625 is a file upload validation vulnerability in the Easy Discuss component for Joomla. User-provided uploads are checked solely by file extensions, with no MIME type validation performed, allowing potential bypass via files disguised with permitted extensions. Published on 2026-01-16, the vulnerability is rated 8.8 on the CVSS v3.1 scale (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) and maps to CWE-434 (Unrestricted Upload of File with Dangerous Type).
An attacker with low privileges, such as an authenticated Joomla user, can exploit this vulnerability remotely over the network with low complexity and no user interaction required. Successful exploitation enables high-impact compromise of confidentiality, integrity, and availability, potentially through uploading and executing malicious files like web shells.
Mitigation details are available via the vendor reference at https://stackideas.com/easydiscuss. Security practitioners should check for patches or updates from Stack Ideas, the Easy Discuss developer, and apply them promptly to affected Joomla installations.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-2937
Vulnerability details
User provided uploads to the Easy Discuss component for Joomla aren't properly validated. Uploads are purely checked by file extensions, no mime type checks are happening.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Unrestricted file upload (CWE-434) in public-facing Joomla component directly enables remote web shell deployment via T1190 exploitation and T1505.003 server software component.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly mandates validation of user-provided file uploads beyond mere extension checks, including MIME types, to prevent bypass with disguised dangerous files.
Requires timely identification, reporting, and remediation of the specific file upload validation flaw via vendor patches.
Deploys malicious code protection mechanisms to scan and block execution of dangerous files uploaded via extension spoofing.