CVE-2026-5821

Description

The Image Optimizer plugin for WordPress is vulnerable to arbitrary file deletion in versions up to and including 1.7.4. This is due to insufficient path validation in the Image_Backup::remove() function where backup file paths stored in post meta are used directly in file deletion operations without verifying they are within the uploads directory. The plugin stores backup file paths in the image_optimizer_metadata post meta field and trusts these paths completely when deleting backups on the delete_attachment hook. An authenticated attacker with Author-level access can edit the image_optimizer_metadata post meta on their own attachments via WordPress's Custom Fields interface, injecting arbitrary absolute file paths into the backups array. When the attacker subsequently deletes the attachment, the plugin calls File_System::delete() on each path without validation. This makes it possible for authenticated attackers, with Author-level access and above, to delete arbitrary files on the server within the web server's filesystem permissions, potentially leading to denial of service, data loss, or security degradation.

CVSS v3.1 Score

8.1

HIGH

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

EPSS — Exploit Prediction

0.0035

Probability of exploitation

0.27%

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-73 CWE-73

References

Other References

https://plugins.trac.wordpress.org/browser/image-optimization/tags/1.7.3/classes/image/image-backup.php#L117 https://plugins.trac.wordpress.org/browser/image-optimization/tags/1.7.3/classes/image/image-meta.php#L97 https://plugins.trac.wordpress.org/browser/image-optimization/tags/1.7.3/modules/backups/components/handle-backups-removing.php#L19 https://plugins.trac.wordpress.org/browser/image-optimization/trunk/classes/image/image-backup.php#L117 https://plugins.trac.wordpress.org/browser/image-optimization/trunk/classes/image/image-meta.php#L97 https://plugins.trac.wordpress.org/browser/image-optimization/trunk/modules/backups/components/handle-backups-removing.php#L19 https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=3557772%40image-optimization&new=3557772%40image-optimization&sfp_email=&sfph_mail= https://www.wordfence.com/threat-intel/vulnerabilities/id/a1a00374-e9d6-46f9-a28c-cb7768505787?source=cve

Frequently Asked Questions

What is CVE-2026-5821? +

The Image Optimizer plugin for WordPress is vulnerable to arbitrary file deletion in versions up to and including 1.7.4. This is due to insufficient path validation in the Image_Backup::remove() function where backup file paths stored in post meta are used directly in file deletion operations without verifying they are within the uploads directory. The plugin stores backup file paths in the image_optimizer_metadata post meta field and trusts these paths completely when deleting backups on the delete_attachment hook. An authenticated attacker with Author-level access can edit the image_optimizer_metadata post meta on their own attachments via WordPress's Custom Fields interface, injecting arbitrary absolute file paths into the backups array. When the attacker subsequently deletes the attachment, the plugin calls File_System::delete() on each path without validation. This makes it possible for authenticated attackers, with Author-level access and above, to delete arbitrary files on the server within the web server's filesystem permissions, potentially leading to denial of service, data loss, or security degradation. It has a CVSS v3.1 base score of 8.1 (HIGH).

How severe is CVE-2026-5821? +

CVE-2026-5821 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0035, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-5821? +

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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