# 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. - **Severity:** High 7.5 (`CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 27 Apr 2026 - **Updated:** 29 Apr 2026 - **Also known as:** CLSA-2026-1779238043, CLSA-2026-1779324467, CLSA-2026-1779410892, ECHO-daf7-d2da-7209, GHSA-56v8-86gj-66jp, RHLW-2026-847d178ef0f52697, ROOT-APP-MAVEN-CVE-2026-40972 ## 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 (Observable Timing Discrepancy) ## 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 | Ecosystem | 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 | | `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: 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](https://insights.sbomify.com/CVE-2023-20873/): Spring Boot Security Bypass with Wildcard Pattern Matching on Cloud Foundry (critical 9.8) - [CVE-2026-40976](https://insights.sbomify.com/CVE-2026-40976/): Spring Boot's default security filter chain has no authorization rule with Actuator but without Health (critical 9.1) - [CVE-2026-22731](https://insights.sbomify.com/CVE-2026-22731/): Authentication Bypass under Actuator Health groups paths (high 8.2) - [CVE-2026-22733](https://insights.sbomify.com/CVE-2026-22733/): Authentication Bypass under Actuator CloudFoundry endpoints (high 8.2) - [CVE-2022-27772](https://insights.sbomify.com/CVE-2022-27772/): Temporary Directory Hijacking to Local Privilege Escalation Vulnerability in org.springframework.boot:spring-boot (high 7.8) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-40972 and fix it if it is affected. What it is: 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. Exploitation: There is no known exploitation of CVE-2026-40972 in the wild and no public exploit code. Affected packages and fixed versions: - org.springframework.boot:spring-boot-devtools (Maven): affected all versions up to 2.7.32; no fix listed - org.springframework.boot:spring-boot-devtools (Maven): affected all versions up to 2.7.32; no fix listed - org.springframework.boot:spring-boot-devtools (Maven): affected from 3.3.0 up to 3.3.18; no fix listed - org.springframework.boot:spring-boot-devtools (Maven): affected from 3.3.0 up to 3.3.18; no fix listed - org.springframework.boot:spring-boot-devtools (Maven): affected from 3.4.0 up to 3.4.15; no fix listed - org.springframework.boot:spring-boot-devtools (Maven): affected from 3.4.0 up to 3.4.15; no fix listed - org.springframework.boot:spring-boot-devtools (Maven): affected from 3.5.0; fixed in 3.5.14 - org.springframework.boot:spring-boot-devtools (Maven): affected from 3.5.0; fixed in 3.5.14 - org.springframework.boot:spring-boot-devtools (Maven): affected from 4.0.0; fixed in 4.0.6 - org.springframework.boot:spring-boot-devtools (Maven): affected from 4.0.0; fixed in 4.0.6 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-40972/ (Markdown: https://insights.sbomify.com/CVE-2026-40972/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40972 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40972 - OSV: https://osv.dev/vulnerability/CVE-2026-40972 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-40972/ Summaries are generated and may contain mistakes; the official description above is the record.