CVE-2026-77929: File Upload RCE (CVSS 8.8)

Description

ClipBucket v5 before 5.5.3-#182 contains a file upload vulnerability that allows authenticated users to achieve remote code execution by uploading a PHP file with valid image magic bytes through the photo upload endpoint. The FileUpload::manageFile() function in fileupload.class.php fails to update the file extension after MIME validation, allowing an attacker-controlled .php extension to persist on disk and execute as PHP via PHP-FPM when the uploaded file is retrieved.

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CVSS v3.1 Score

8.8

HIGH

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

EPSS — Exploit Prediction

0.0094

Probability of exploitation

0.60%

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

https://github.com/MacWarrior/clipbucket-v5/commit/61cce55ab26ef88fb782dfde47b44c17c56978cd https://github.com/MacWarrior/clipbucket-v5/releases/tag/5.5.3-%23182 https://www.vulncheck.com/advisories/clipbucket-remote-code-execution-via-photo-upload-endpoint

Frequently Asked Questions

What is CVE-2026-77929? +

ClipBucket v5 before 5.5.3-#182 contains a file upload vulnerability that allows authenticated users to achieve remote code execution by uploading a PHP file with valid image magic bytes through the photo upload endpoint. The FileUpload::manageFile() function in fileupload.class.php fails to update the file extension after MIME validation, allowing an attacker-controlled .php extension to persist on disk and execute as PHP via PHP-FPM when the uploaded file is retrieved. It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-77929? +

CVE-2026-77929 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0094, placing it in the 1th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-77929? +

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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