CVE-2026-15965
HIGHDescription
The MaxUpload – Big File Uploads – Increase Maximum File Upload Size plugin for WordPress is vulnerable to Arbitrary File Upload in all versions up to, and including, 1.4.0 via the handle_upload function. This is due to a filename-validation mismatch in the handle_upload function where extension and MIME checks are applied to the uploaded chunk's filename but not to the final assembled filename derived from the resumableFilename parameter. This makes it possible for unauthenticated attackers to upload files that may be executable, which makes remote code execution possible.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Moderate risk: more likely to be exploited than 45% of all known CVEs.
References
Related Vulnerabilities
Other CWE-434 (Unrestricted File Upload) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2017-12617 | High | 8.1 | 100% | KEV | Fix |
| CVE-2018-15961 | Critical | 9.8 | 100% | KEV | - |
| CVE-2021-31207 | Medium | 6.6 | 100% | KEV + Ransom | Fix |
| CVE-2017-12615 | High | 8.1 | 100% | KEV + Ransom | - |
| CVE-2025-31324 | Critical | 10.0 | 100% | KEV + Ransom | - |
| CVE-2024-50623 | Critical | 9.8 | 99% | KEV + Ransom | Fix |
Common questions
How do I fix CVE-2026-15965?
No published fix for CVE-2026-15965 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-15965 being actively exploited?
Not that we know of. CVE-2026-15965 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.58% is the estimated probability that it will be exploited in the next 30 days. That is higher than 45% of all scored CVEs.
How severe is CVE-2026-15965?
CVE-2026-15965 has a CVSS v3 base score of 8.8, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-20.