Arbitrary file upload in 10web Booster – Website Speed Optimization, Cache & Page Optimizer

CVE-2026-108587

The 10Web Booster – Website speed optimization, Cache & Page Speed optimizer plugin for WordPress is vulnerable to Arbitrary File Upload in all versions up to, and including, 2.34.10 via the compressCustom function. This is due to missing file type validation and extension filtering on the page_id parameter, combined with a world-readable leaked nonce that bypasses authentication checks. This makes it possible for unauthenticated attackers to upload files that may be executable, which makes remote code execution possible. This exploit chain requires obtaining the plugin's REST nonce (tenwebio_rest), which is automatically serialized to a world-readable file under wp-content/uploads/ whenever a bulk optimisation batch pauses; because the nonce is generated in a cron/loopback context with a user ID of 0, it is valid for unauthenticated visitors.

Vulnerability class: Unrestricted File Upload

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-108587?
CVE-2026-108587 is a critical-severity vulnerability in 10web Booster – Website Speed Optimization, Cache & Page Optimizer, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2026-10-15.
How severe is CVE-2026-108587?
Critical severity. CVSS v3 base score is 9.8 out of 10.