CVE-2025-27821
HIGHCVE-2025-27821 is a high-severity (CVSS 7.3) Out-of-bounds Write vulnerability in org.apache.hadoop:hadoop-hdfs-native-client. O3 Security confirms whether CVE-2025-27821 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
HDFS native client: Out of bounds write in URI parser of native HDFS client
Blast Radius
org.apache.hadoop:hadoop-hdfs-native-clientReal-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
Out-of-bounds Write vulnerability in Apache Hadoop HDFS native client.
This issue affects Apache Hadoop: from 3.2.0 before 3.4.2.
Users are recommended to upgrade to version 3.4.2, which fixes the issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.hadoop:hadoop-hdfs-native-client | ≥ 3.2.0&&< 3.4.2 | 3.4.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.hadoop:hadoop-hdfs-native-client. 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.apache.hadoop:hadoop-hdfs-native-client to 3.4.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-27821 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-2025-27821 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-2025-27821. 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-2025-27821 in your dependencies?
O3 detects CVE-2025-27821 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.