CVE-2021-21290

What it is

Netty is an open-source, asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. In Netty before version 4.1.59.Final there is a vulnerability on Unix-like systems involving an insecure temp file. 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. On unix-like systems, the temporary directory is shared between all user. As such, writing to this directory using APIs that do not explicitly set the file/directory permissions can lead to information disclosure. Of note, this does not impact modern MacOS Operating Systems. The method "File.createTempFile" on unix-like systems creates a random file, but, by default will create this file with the permissions "-rw-r--r--". Thus, if sensitive information is written to this file, other local users can read this information. This is the case in netty's "AbstractDiskHttpData" is vulnerable. This has been fixed in version 4.1.59.Final. As a workaround, one may 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.

At a glance

Exploitability

Can be exploited locally on the machine without logging in. High risk of data exposure.

Exploit odds

1.8% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-02-08 20:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-08 22:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.8% in the next 30 days (EPSS).
• Severity: 6.2 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-02-08 20:15 UTC

Last modified

2026-10-08 22:17 UTC

Exploit probability

1.8% · EPSS, next 30 days

Weakness

CWE-378

Record status

Modified

Affected

• Netty < 4.1.59
• Debian Linux 9.0
• Debian Linux 10.0
• Quarkus ≤ 1.13.7
• Oracle Banking Corporate Lending Process Management 14.2.0
• Oracle Banking Corporate Lending Process Management 14.3.0
• Oracle Banking Corporate Lending Process Management 14.5.0
• Oracle Banking Credit Facilities Process Management 14.2.0

Attack profile CVSS 3.1 · 6.2

Attack vector

Local

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-21290.md and follow it. Check whether this project is affected by CVE-2021-21290. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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