CVE-2021-29485
HIGHCVE-2021-29485 is a high-severity (CVSS 8.8) Deserialization of Untrusted Data vulnerability in io.ratpack:ratpack-core. O3 Security confirms whether CVE-2021-29485 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Remote Code Execution Vulnerability in Session Storage
Real-World Exposure
io.ratpack:ratpack-coreReal-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
Ratpack is a toolkit for creating web applications. In versions prior to 1.9.0, a malicious attacker can achieve Remote Code Execution (RCE) via a maliciously crafted Java deserialization gadget chain leveraged against the Ratpack session store. If one's application does not use Ratpack's session mechanism, it is not vulnerable. Ratpack 1.9.0 introduces a strict allow-list mechanism that mitigates this vulnerability when used. Two possible workarounds exist. The simplest mitigation for users of earlier versions is to reduce the likelihood of attackers being able to write to the session data store. Alternatively or additionally, the allow-list mechanism could be manually back ported by providing an alternative implementation of SessionSerializer that uses an allow-list.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.ratpack:ratpack-core | all versions | 1.9.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.ratpack:ratpack-core. 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 io.ratpack:ratpack-core to 1.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-29485 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-2021-29485 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-2021-29485. 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-2021-29485 in your dependencies?
O3 detects CVE-2021-29485 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.