CVE-2026-31868Network attack vector

Stored XSS via incomplete upload type blocklist

Published Mar 11, 2026 · Updated Mar 11, 2026

Stored XSS in Parse Platform Parse Server before 8.6.30 and 9.0.0 through 9.6.0-alpha.3 allows remote attackers to execute script in users' browsers. The default fileUpload.fileExtensions blocklist omits several browser-renderable extensions and MIME types, so uploaded active content is served from the Parse Server domain. Exploitation requires a user to access the uploaded file URL and permits theft of session tokens, redirection, or actions in that user's context.

CVSS severity6.3
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Parse Platform Parse Server before 8.6.30 and 9.0.0 through 9.6.0-alpha.3 allows remote attackers to execute script in users' browsers. The default fileUpload.fileExtensions blocklist omits several browser-renderable extensions and MIME types, so uploaded active content is served from the Parse Server domain. Exploitation requires a user to access the uploaded file URL and permits theft of session tokens, redirection, or actions in that user's context.

The record

CVE
CVE-2026-31868
Published
Mar 11, 2026
Updated
Mar 11, 2026
Vendor
Parse Platform
Product
Parse Server
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 8.6.30
  2. Affected versionversion=>= 9.0.0 < 9.6.0-alpha.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Parse Platform · Parse Serverversion=< 8.6.30; version=>= 9.0.0 < 9.6.0-alpha.4

Published CVSS scores

6.3GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
6.1NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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