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CVE-2021-21290— Local Information Disclosure Vulnerability in Netty on Unix-Like systems due temporary files

Quick assessment

Affected
netty netty
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Netty是Netty社区的一款非阻塞I/O客户端-服务器框架，它主要用于开发Java网络应用程序，如协议服务器和客户端等。 Netty 4.1.59之前版本存在安全漏洞，该漏洞源于当netty的多部分解码器被使用时，如果磁盘上的临时存储被启用，则本地信息可以通过本地系统临时目录进行公开。在类unix系统中，所有用户共享临时目录。因此，使用没有显式设置文件/目录权限的api写入该目录可能导致信息泄露。值得注意的是，这并不影响现代的MacOS操作系统。法”文件。createTempFile"在类unix系统

CVSS 6.2 · Medium EPSS 1.78% · P77

Possible ATT&CK Techniques 1 AI

T1005 · Data from Local System
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I. Basic Information for CVE-2021-21290

Vulnerability Information
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Vulnerability Title
Local Information Disclosure Vulnerability in Netty on Unix-Like systems due temporary files
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
创建拥有不安全权限的临时文件
Source: CVE Program / CVE List V5
Vulnerability Title
Netty 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Netty是Netty社区的一款非阻塞I/O客户端-服务器框架，它主要用于开发Java网络应用程序，如协议服务器和客户端等。 Netty 4.1.59之前版本存在安全漏洞，该漏洞源于当netty的多部分解码器被使用时，如果磁盘上的临时存储被启用，则本地信息可以通过本地系统临时目录进行公开。在类unix系统中，所有用户共享临时目录。因此，使用没有显式设置文件/目录权限的api写入该目录可能导致信息泄露。值得注意的是，这并不影响现代的MacOS操作系统。法”文件。createTempFile"在类unix系统
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
netty netty < 4.1.59.Final -

II. Public POCs for CVE-2021-21290

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III. Intelligence Information for CVE-2021-21290

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Patches & Fixes for CVE-2021-21290 (1)

Vendor Advisories for CVE-2021-21290 (7)

Mailing List Discussions for CVE-2021-21290 (30)

IV. Related Vulnerabilities

Same product: netty
Same vendor: netty
Same weakness: CWE-378

V. Comments for CVE-2021-21290

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