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Spring Web Flow JS RemotingHandler renders non-HTML Response as HTML

Moderate severity GitHub Reviewed Published Jun 11, 2026 to the GitHub Advisory Database • Updated Aug 18, 2026

Package

maven org.springframework.webflow:spring-webflow (Maven)

Affected versions

= 4.0.0
>= 3.0.0, <= 3.0.1
<= 2.5.1

Patched versions

4.0.1
3.0.2

Description

Spring Web Flow's JavaScript RemotingHandler renders the body of an error response as HTML even when the response is not "text/html", which can result in a scripting attack in the user's browser if the error response from the server contains error details with input reflected from an attacker.

Affected versions:
Spring Web Flow 4.0.0; 3.0.0 through 3.0.1; 2.5.0 through 2.5.1.

References

Published by the National Vulnerability Database Jun 11, 2026
Published to the GitHub Advisory Database Jun 11, 2026
Reviewed Aug 18, 2026
Last updated Aug 18, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(10th percentile)

Weaknesses

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.

CVE ID

CVE-2026-40986

GHSA ID

GHSA-hw5c-xm3c-v96w

Source code

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