CVE-2026-108587: File Upload RCE (CVSS 9.8)

Description

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.

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CVSS v3.1 Score

9.8

CRITICAL

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

EPSS — Exploit Prediction

0.0092

Probability of exploitation

0.59%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-434 Unrestricted Upload

References

Other References

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-108587? +

CVE-2026-108587 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0092, placing it in the 1th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-108587? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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