GHSA-269q-hmxg-m83q
MEDIUMLocal Information Disclosure Vulnerability in io.netty:netty-codec-http
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
io.netty:netty-codec-httpReal-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
Description
GHSA-5mcr-gq6c-3hq2 (CVE-2021-21290) contains an insufficient fix for the vulnerability identified.
Impact
When netty's multipart decoders are used local information disclosure can occur via the local system temporary directory if temporary storing uploads on the disk is enabled.
This only impacts applications running on Java version 6 and lower. Additionally, this vulnerability impacts code running on Unix-like systems, and very old versions of Mac OSX and Windows as they all share the system temporary directory between all users.
Vulnerability Details
To fix the vulnerability the code was changed to the following:
@SuppressJava6Requirement(reason = "Guarded by version check")
public static File createTempFile(String prefix, String suffix, File directory) throws IOException {
if (javaVersion() >= 7) {
if (directory == null) {
return Files.createTempFile(prefix, suffix).toFile();
}
return Files.createTempFile(directory.toPath(), prefix, suffix).toFile();
}
if (directory == null) {
return File.createTempFile(prefix, suffix);
}
File file = File.createTempFile(prefix, suffix, directory);
// Try to adjust the perms, if this fails there is not much else we can do...
file.setReadable(false, false);
file.setReadable(true, true);
return file;
}
Unfortunately, this logic path was left vulnerable:
if (directory == null) {
return File.createTempFile(prefix, suffix);
}
This file is still readable by all local users.
Patches
Update to 4.1.77.Final
Workarounds
Specify your own java.io.tmpdir when you start the JVM or use DefaultHttpDataFactory.setBaseDir(...) to set the directory to something that is only readable by the current user or update to Java 7 or above.
References
- CWE-378: Creation of Temporary File With Insecure Permissions
- CWE-379: Creation of Temporary File in Directory with Insecure Permissions
For more information
If you have any questions or comments about this advisory:
Open an issue in netty
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.netty:netty-codec-http | all versions | 4.1.77.Final |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty:netty-codec-http. 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.netty:netty-codec-http to 4.1.77.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-269q-hmxg-m83q 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 GHSA-269q-hmxg-m83q 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 GHSA-269q-hmxg-m83q. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-269q-hmxg-m83q in your dependencies?
O3 detects GHSA-269q-hmxg-m83q across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.