Parse Server vulnerable to stored cross-site scripting (XSS) via SVG file upload
Impact
A stored cross-site scripting (XSS) vulnerability allows any authenticated user to upload an SVG file containing JavaScript. The file is served inline with Content-Type: image/svg+xml and without protective headers, causing the browser to execute embedded scripts in the Parse Server origin. This can be exploited to steal session tokens from localStorage and achieve account takeover.
The default fileExtensions option blocks HTML file extensions but does not block SVG, which is a well-known XSS vector. All Parse Server deployments where file upload is enabled for authenticated users (the default) are affected.
Patches
The fix adds svg (case-insensitive) to the default file extension denylist. The default regex changes from ^(?![xXsS]?[hH][tT][mM][lL]?$) to ^(?!([xXsS]?[hH][tT][mM][lL]?|[sS][vV][gG])$).
Workarounds
Configure the fileExtensions option to explicitly block SVG uploads:
{
fileUpload: {
fileExtensions: ['^(?!([xXsS]?[hH][tT][mM][lL]?|[sS][vV][gG])$)']
}
}References
- GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-hcj7-6gxh-24ww
- Fix Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.5.2-alpha.4
- Fix Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.17
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | parse-server | >= 9.0.0, < 9.5.2-alpha.4, < 8.6.17 | 9.5.2-alpha.4, 8.6.17 |
References
- https://github.com/parse-community/parse-server/security/advisories/GHSA-hcj7-6gxh-24ww
- https://nvd.nist.gov/vuln/detail/CVE-2026-30948
- https://github.com/parse-community/parse-server
- https://github.com/parse-community/parse-server/releases/tag/8.6.17
- https://github.com/parse-community/parse-server/releases/tag/9.5.2-alpha.4
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:N/VA:N/SC:H/SI:H/SA:N- Weakness (CWE)
CWE-79- Platform
- npm
- Package
parse-server- Disclosed
- 11.03.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-hcj7-6gxh-24ww - CC BY 4.0
Vulnerability history: parse-server
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 116
- First → latest
- 06.2019 06.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 17
- High 49
- Medium 40
- Low 10
Disclosures per year
- 2019: 2
- 2020: 4
- 2021: 4
- 2022: 12
- 2023: 5
- 2024: 4
- 2025: 6
- 2026: 79
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Parse Server vulnerable to stored cross-site scripting (XSS) via SVG file upload this entry
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