CVE-2021-30149: Composr 10.0.36 allows upload and execution of PHP files.

PriorityP270critical9.8CVSS 3.1

AVNACLPRNUINSUCHIHAH

EXPLOIT

EPSS

10.06%

95.0th percentile

Composr 10.0.36 allows upload and execution of PHP files.

Affected

1 ranges

Vendor	Product	Version range	Fixed in
ocproducts	composr	—	—

Detection & IOCsextracted from sources · hover to see the quote

→Attacker uploads a file via the 'Upload In Bulk' gallery function and tampers the HTTP request to change the file extension from .jpg to .php, bypassing server-side extension validation ↗
→The standard galleries uploader correctly rejects PHP uploads with a 'hacking attempts' error; only the 'Upload In Bulk' code path is vulnerable — focus detection on that specific endpoint ↗
→Alert on successful HTTP responses (e.g. 200/201) to Composr gallery upload endpoints where the uploaded filename ends in .php, indicating a bypassed extension check and potential webshell placement ↗

·The vulnerability affects specifically Composr CMS version 10.0.36; other versions are not confirmed vulnerable by the available sources ↗
·The bypass only works via the 'Upload In Bulk' gallery function; the standard gallery uploader correctly enforces the PHP extension block, so detection rules scoped only to the main uploader endpoint will miss exploitation ↗

CVSS provenance

nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvdv2.07.5HIGHAV:N/AC:L/Au:N/C:P/I:P/A:P

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