CVE-2026-32728: parse-server · Cross-site Scripting
Affects parse-serverSource CVE Database V5
Not known to be exploited · CVSS 8.3 High : upgrade to 9.6.0-alpha.15 or 8.6.41 soon.
Data as of 30 Oct 2026, 20:25 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 9.6.0-alpha.15, 8.6.41
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:L/VA:N/SC:H/SI:L/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 18 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade parse-server to 9.6.0-alpha.15 or 8.6.41; parse-community/parse-server to 8.6.41.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| parse-communityparse-server | Affected
| Fixed in
|
| parse-communityparse-server | Affected
| Fixed in
|
GitHubparse-community/parse-serverpkg:github/parse-community/parse-serverOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
To mitigate this vulnerability, organizations should immediately upgrade parse-server to version 9.6.0-alpha.15, 8.6.41, or later where the issue is fixed. In addition, developers must configure the fileUpload.fileExtensions option as a strict allowlist containing only the file extensions necessary for their application, rather than relying on the default blocklist. This proactive approach reduces the risk of new or unlisted dangerous extensions being exploited. It is also critical to validate and sanitize all uploaded files on the server side, including stripping or normalizing MIME parameters in the Content-Type header before any extension validation. Implementing Content Security Policy (CSP) headers can help mitigate the impact of XSS by restricting script execution sources. Regular security audits and penetration testing focusing on file upload functionality should be conducted to detect similar issues. Monitoring logs for suspicious file uploads and anomalous user behavior can aid early detection of exploitation attempts. Finally, educating developers about the risks of improper input validation and the limitations of blocklists versus allowlists will improve long-term security posture.
Description
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.6.0 and 8.6.41, an attacker who is allowed to upload files can bypass the file extension filter by appending a MIME parameter (e.g. `;charset=utf-8`) to the `Content-Type` header. This causes the extension validation to fail matching against the blocklist, allowing active content to be stored and served under the application's domain. In addition, certain XML-based file extensions that can render scripts in web browsers are not included in the default blocklist. This can lead to stored XSS attacks, compromising session tokens, user credentials, or other sensitive data accessible via the browser's local storage. The fix in versions 9.6.0 and 8.6.41 strips MIME parameters from the `Content-Type` header before validating the file extension against the blocklist. The default blocklist has also been extended to include additional XML-based extensions (`xsd`, `rng`, `rdf`, `rdf+xml`, `owl`, `mathml`, `mathml+xml`) that can render active content in web browsers. Note that the `fileUpload.fileExtensions` option is intended to be configured as an allowlist of file extensions that are valid for a specific application, not as a denylist. The default denylist is provided only as a basic default that covers most common problematic extensions. It is not intended to be an exhaustive list of all potentially dangerous extensions. Developers should not rely on the default value, as new extensions that can render active content in browsers might emerge in the future. As a workaround, configure the `fileUpload.fileExtensions` option to use an allowlist of only the file extensions that your application needs, rather than relying on the default blocklist.
References
- github.com/parse-community/parse-server/security/advisories/GHSA-42ph-pf9q-cr72 (opens in a new tab)
- github.com/parse-community/parse-server/pull/10191 (opens in a new tab)
- github.com/parse-community/parse-server/pull/10192 (opens in a new tab)
- github.com/parse-community/parse-server/commit/4f53ab3cad5502a51a509d53f999e00ff7217b8d (opens in a new tab)
- github.com/parse-community/parse-server/commit/c7599c577a02b97eb5e76d4e20517b0283ae73c8 (opens in a new tab)