CVE-2026-40986 Spring Web Flow JS RemotingHandler renders non-HTML Response as HTML
Attackers can execute scripts in user browsers via reflected input in error responses rendered as HTML by Spring Web Flow's RemotingHandler.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-40986?
CVE-2026-40986 is a medium-severity cross-site scripting vulnerability in Spring Web Flow, published on 11 Jun 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-79
Which versions are affected by CVE-2026-40986?
6 open source packages ship an affected version, including org.springframework.webflow:spring-webflow. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
org.springframework.webflow:spring-webflow Maven | All versions to 2.5.1 | None |
org.springframework.webflow:spring-webflow Maven | All versions to 2.5.1 | None |
org.springframework.webflow:spring-webflow Maven | From 3.0.0 | 3.0.2 |
org.springframework.webflow:spring-webflow Maven | From 3.0.0 | 3.0.2 |
org.springframework.webflow:spring-webflow Maven | From 4.0.0 | 4.0.1 |
org.springframework.webflow:spring-webflow Maven | From 4.0.0 | 4.0.1 |
Products include Broadcom Spring Web Flow.
How do I fix CVE-2026-40986?
Upgrade org.springframework.webflow:spring-webflow to a fixed version for your release line: 3.0.2 or 4.0.1.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-40986 being exploited?
There is no known exploitation of CVE-2026-40986 in the wild and no public exploit code.
Other vulnerabilities in Spring Web Flow
Sources
Also known as GHSA-hw5c-xm3c-v96w, ROOT-APP-MAVEN-CVE-2026-40986.