CVE-2026-557782.1LowCWE-434

CVE-2026-55778: Parse Server: Stored XSS via non-standard file extension bypassing file upload extension blocklist

parse-community · parse-server

Affected: parse-community parse-server · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.6%probability of exploitation in the next 30 days

46th percentile

050100

Higher than 46% of scored CVEs

2.1LowCVSS 4.0

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

parse-community · parse-server>= 9.0.0-alpha.1, < 9.9.1-alpha.11; < 8.6.81

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Unrestricted File Upload · File and Path Handling
Vendor: parse-community
Published: July 2026
Band: Unlikely (under 1%), July 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-55778 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.