CVE-2026-40972
HIGHCVE-2026-40972 is a high-severity (CVSS 7.5) CWE-208 vulnerability in org.springframework.boot:spring-boot-devtools. O3 Security confirms whether CVE-2026-40972 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Spring Boot DevTools remote secret comparison is vulnerable to timing attacks
Blast Radius
org.springframework.boot:spring-boot-devtools☕org.springframework.boot:spring-boot-devtools☕org.springframework.boot:spring-boot-devtools☕org.springframework.boot:spring-boot-devtools☕org.springframework.boot:spring-boot-devtoolsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.springframework.boot:spring-boot-devtools | ≥ 4.0.0&&< 4.0.6 | 4.0.6 |
| ☕Maven | org.springframework.boot:spring-boot-devtools | ≥ 3.5.0&&< 3.5.14 | 3.5.14 |
| ☕Maven | org.springframework.boot:spring-boot-devtools | ≥ 3.4.0 | No fix |
| ☕Maven | org.springframework.boot:spring-boot-devtools | ≥ 3.3.0 | No fix |
| ☕Maven | org.springframework.boot:spring-boot-devtools | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.springframework.boot:spring-boot-devtools. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update org.springframework.boot:spring-boot-devtools to 4.0.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-40972 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-40972 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-40972. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-40972 in your dependencies?
O3 detects CVE-2026-40972 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.