Answer in brief
CVE-2026-55778 records a Low severity (CVSS 2.1) vulnerability in Parse Server: Stored XSS via non-standard file extension bypassing file upload extension blocklist. The current sources do not mark it as known exploited. The current feed maps parse-community/parse-server (generic), parse-server (npm), parse-server (npm). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 2.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps parse-community/parse-server (generic), parse-server (npm), parse-server (npm). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| parse-community/parse-servergeneric | >= 9.0.0-alpha.1, < 9.9.1-alpha.11 || < 8.6.81 | Not reported |
| parse-servernpm | >=9.0.0,<9.9.1-alpha.11 | 9.9.1-alpha.11 |
| parse-servernpm | <=8.6.80 | 8.6.81 |
Published upstream
Jul 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 10, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 19, 2026
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.
Quoted source text, attributed separately from HOL analysis.