Postiz is an AI social media scheduling tool. Prior to version 2.21.6, a file upload validation bypass allows any authenticated user to upload arbitrary HTML, SVG, or other executable file types to the server by spoofing the Content-Type header. The uploaded files are then served by nginx with a Content-Type derived from their original extension (text/html, image/svg+xml), enabling Stored Cross-Site Scripting (XSS) in the context of the application's origin. This can lead to session riding, account takeover, and full compromise of other users' accounts. Version 2.21.6 contains a fix.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-345",
"CWE-434",
"CWE-79"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40487.json"
}{
"cpe": "cpe:2.3:a:gitroom:postiz:*:*:*:*:*:*:*:*",
"extracted_events": [
{
"introduced": "0"
},
{
"fixed": "2.21.6"
}
],
"source": [
"AFFECTED_FIELD",
"CPE_RANGE",
"REFERENCES"
]
}