Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.9.1-alpha.11 and 8.6.81, the default fileUpload.fileExtensions blocklist could be bypassed by uploading a file with a non-standard or compound extension and dangerous content type, allowing storage adapters such as S3 and GCS to serve attacker-supplied active content and enable stored cross-site scripting. This issue is fixed in versions 9.9.1-alpha.11 and 8.6.81.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-434"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55778.json"
}{
"extracted_events": [
{
"introduced": "9.0.0-alpha.1"
},
{
"fixed": "9.9.1-alpha.11"
},
{
"introduced": "0"
},
{
"fixed": "8.6.81"
}
],
"source": [
"AFFECTED_FIELD",
"REFERENCES"
]
}