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

published 2026-06-11 4 mo ago modified 2026-09-04 2 mo ago also GHSA-hw5c-xm3c-v96w , EUVD-2026-36201

cvss: 4.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits: 0; none known

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.

Patch / fix

fixed in 2

maven org.springframework.webflow:spring-webflow 3.0.2, 4.0.1
Spring Spring Web Flow 2.5.2, 3.0.1.1, 4.0.0.1

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 4 mo ago (2026-06-11)

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	4.8	CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N
GitHub	3.1	4.8	CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N

Affected packages

ecosystem	package	affected	fixed in
maven	org.springframework.webflow:spring-webflow	>=4.0.0, <4.0.1 >=3.0.0, <3.0.2 <=2.5.1	4.0.1 3.0.2

Affected products

Spring Spring Web Flow

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

spring.io /security/cve-2026-40986
web, vendor-advisory
nvd.nist.gov /vuln/detail/CVE-2026-40986
advisory
github.com /spring-projects/spring-webflow
package

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary