CVE-2026-40972 Spring Boot DevTools remote secret comparison is vulnerable to timing attacks
A timing attack in Spring Boot DevTools allows attackers to discover the remote secret, potentially leading to remote code execution via class uploads.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-40972?
CVE-2026-40972 is a high-severity vulnerability in Spring Boot, published on 27 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
An attacker on the same network as the remote application may be able to utilize a timing attack to discover information about the remote secret. In extreme circumstances this could result in the attacker determining the secret and uploading changed classes, thereby achieving remote code execution in the remote application.
Affected: Spring Boot 4.0.0–4.0.5 (fix 4.0.6), 3.5.0–3.5.13 (fix 3.5.14), 3.4.0–3.4.15 (fix 3.4.16), 3.3.0–3.3.18 (fix 3.3.19), 2.7.0–2.7.32 (fix 2.7.33); DevTools remote secret comparison. Versions that are no longer supported are also affected per vendor advisory.
Weakness: CWE-208
Which versions are affected by CVE-2026-40972?
10 open source packages ship an affected version, including org.springframework.boot:spring-boot-devtools. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
org.springframework.boot:spring-boot-devtools Maven | All versions to 2.7.32 | None |
org.springframework.boot:spring-boot-devtools Maven | All versions to 2.7.32 | None |
org.springframework.boot:spring-boot-devtools Maven | From 3.3.0 to 3.3.18 | None |
org.springframework.boot:spring-boot-devtools Maven | From 3.3.0 to 3.3.18 | None |
org.springframework.boot:spring-boot-devtools Maven | From 3.4.0 to 3.4.15 | None |
org.springframework.boot:spring-boot-devtools Maven | From 3.4.0 to 3.4.15 | None |
4 more packages
org.springframework.boot:spring-boot-devtools Maven | From 3.5.0 | 3.5.14 |
org.springframework.boot:spring-boot-devtools Maven | From 3.5.0 | 3.5.14 |
org.springframework.boot:spring-boot-devtools Maven | From 4.0.0 | 4.0.6 |
org.springframework.boot:spring-boot-devtools Maven | From 4.0.0 | 4.0.6 |
Products include Vmware Spring Boot.
How do I fix CVE-2026-40972?
Upgrade org.springframework.boot:spring-boot-devtools to a fixed version for your release line: 3.5.14 or 4.0.6.
Is CVE-2026-40972 being exploited?
There is no known exploitation of CVE-2026-40972 in the wild and no public exploit code.
Other vulnerabilities in Spring Boot
- CVE-2023-20873 Spring Boot Security Bypass with Wildcard Pattern Matching on Cloud Foundry
- CVE-2026-40976 Spring Boot's default security filter chain has no authorization rule with Actuator but without Health
- CVE-2026-22731 Authentication Bypass under Actuator Health groups paths
- CVE-2026-22733 Authentication Bypass under Actuator CloudFoundry endpoints
- CVE-2022-27772 Temporary Directory Hijacking to Local Privilege Escalation Vulnerability in org.springframework.boot:spring-boot
Sources
Also known as CLSA-2026-1779238043, CLSA-2026-1779324467, CLSA-2026-1779410892, ECHO-daf7-d2da-7209, GHSA-56v8-86gj-66jp, RHLW-2026-847d178ef0f52697 and 1 more.