CVE-2026-33331Public exploitNetwork attack vector

Stored XSS via unescaped JSON embedding

Published Mar 24, 2026 · Updated Mar 24, 2026

Stored XSS in middleapi oRPC before 1.13.9 allows remote attackers to execute JavaScript when a user opens generated OpenAPI documentation. The OpenAPIReferencePlugin renderDocsHtml function inserts stringified specification data into an inline script block without escaping HTML-significant characters, so a closing script tag exits the JSON context. Exploitation requires attacker control of a specification field and a developer or administrator to view the documentation; executed script can steal session data or issue API requests in that viewer's context.

CVSS severity8.2
High
EPSS probability0.29%
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 middleapi oRPC before 1.13.9 allows remote attackers to execute JavaScript when a user opens generated OpenAPI documentation. The OpenAPIReferencePlugin renderDocsHtml function inserts stringified specification data into an inline script block without escaping HTML-significant characters, so a closing script tag exits the JSON context. Exploitation requires attacker control of a specification field and a developer or administrator to view the documentation; executed script can steal session data or issue API requests in that viewer's context.

The record

CVE
CVE-2026-33331
Published
Mar 24, 2026
Updated
Mar 24, 2026
Vendor
middleapi
Product
oRPC
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 24, 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=< 1.13.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

middleapi · oRPCversion=< 1.13.9

Published CVSS scores

8.2GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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