CVE-2021-21290

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.

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.

The CVSSv3.1 score of this vulnerability is calculated to be a 6.2/10

Vulnerability Details

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.

https://github.com/netty/netty/blob/e5951d46fc89db507ba7d2968d2ede26378f0b04/codec-http/src/main/java/io/netty/handler/codec/http/multipart/AbstractDiskHttpData.java#L80-L101

AbstractDiskHttpData is used as a part of the DefaultHttpDataFactory class which is used by HttpPostRequestDecoder / HttpPostMultiPartRequestDecoder.

You may be affected by this vulnerability your project contains the following code patterns:

channelPipeline.addLast(new HttpPostRequestDecoder(...));

channelPipeline.addLast(new HttpPostMultiPartRequestDecoder(...));

Patches

This has been patched in version 4.1.59.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.

References

• CWE-378: Creation of Temporary File With Insecure Permissions
• CWE-379: Creation of Temporary File in Directory with Insecure Permissions

Similar Vulnerabilities

Similar, but not the same.

• JUnit 4 - https://github.com/junit-team/junit4/security/advisories/GHSA-269g-pwp5-87pp
• Google Guava - https://github.com/google/guava/issues/4011
• Apache Ant - https://nvd.nist.gov/vuln/detail/CVE-2020-1945
• JetBrains Kotlin Compiler - https://nvd.nist.gov/vuln/detail/CVE-2020-15824

For more information

If you have any questions or comments about this advisory:

• Open an issue in netty
• Email us here

Original Report

Hi Netty Security Team,

I've been working on some security research leveraging custom CodeQL queries to detect local information disclosure vulnerabilities in java applications. This was the result from running this query against the netty project: https://lgtm.com/query/7723301787255288599/

Netty contains three local information disclosure vulnerabilities, so far as I can tell.

One is here, where the private key for the certificate is written to a temporary file.

https://github.com/netty/netty/blob/e5951d46fc89db507ba7d2968d2ede26378f0b04/handler/src/main/java/io/netty/handler/ssl/util/SelfSignedCertificate.java#L316-L346

One is here, where the certificate is written to a temporary file.

https://github.com/netty/netty/blob/e5951d46fc89db507ba7d2968d2ede26378f0b04/handler/src/main/java/io/netty/handler/ssl/util/SelfSignedCertificate.java#L348-L371

The final one is here, where the 'AbstractDiskHttpData' creates a temporary file if the getBaseDirectory() method returns null. I believe that 'AbstractDiskHttpData' is used as a part of the file upload support? If this is the case, any files uploaded would be similarly vulnerable.

…

A client might overload the server by issue frequent RST frames. This can cause a massive amount of load on the remote system and so cause a DDOS attack.

Impact

This is a DDOS attack, any http2 server is affected and so you should update as soon as possible.

Patches

This is patched in version 4.1.100.Final.

Workarounds

A user can limit the amount of RST frames that are accepted per connection over a timeframe manually using either an own Http2FrameListener implementation or an ChannelInboundHandler implementation (depending which http2 API is used).

References

• https://www.cve.org/CVERecord?id=CVE-2023-44487
• https://blog.cloudflare.com/technical-breakdown-http2-rapid-reset-ddos-attack/
• https://cloud.google.com/blog/products/identity-security/google-cloud-mitigated-largest-ddos-attack-peaking-above-398-million-rps/

Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients.

Security Fix(es):

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.(CVE-2021-21290)

Root has patched GHSA-xpw8-rcwv-8f8p in the io.root.io.netty:netty-codec-http2 package for Root:Maven. Multiple fixed versions available.

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.

TuxCare rebuilt 40 io.netty packages to address 16 CVEs. Fixed in 4.1.52.Final-tuxcare.1.

TuxCare rebuilt 40 io.netty packages to address 5 CVEs. Fixed in 4.1.48.Final-tuxcare.1.

TuxCare rebuilt 6 io.netty packages to address 9 CVEs. Fixed in 4.1.58.Final-tuxcare.1.

TuxCare rebuilt io.netty:netty to address 6 CVEs. Fixed in 3.10.6.Final-tuxcare.1.

TuxCare rebuilt io.netty:netty to address 4 CVEs. Fixed in 3.7.0.Final-tuxcare.1.

TuxCare rebuilt io.netty:netty to address 4 CVEs. Fixed in 3.5.13.Final-tuxcare.1.

TuxCare rebuilt 40 io.netty packages to address 26 CVEs. Fixed in 4.1.53.Final-tuxcare.1.

TuxCare rebuilt 11 io.netty packages to address 21 CVEs. Fixed in 4.1.51.Final-tuxcare.1.

TuxCare rebuilt io.netty:netty to address 4 CVEs. Fixed in 3.6.2.Final-tuxcare.1.

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 (CVE-2021-21290).

These are all security issues fixed in the netty-4.1.60-1.4 package on the GA media of openSUSE Tumbleweed.

Rocky Enterprise Software Foundation Satellite is a systems management tool for Linux-based infrastructure. It allows for provisioning, remote management, and monitoring of multiple Linux deployments with a single centralized tool.

Security Fix(es):

• libsolv: Heap-based buffer overflow in testcase_read() in src/testcase.c (CVE-2021-3200)
• satellite: foreman: Authenticate remote code execution through Sendmail configuration (CVE-2021-3584)
• candlepin: Allow unintended SCA certificate to authenticate Candlepin (CVE-2021-4142)
• candlepin: netty: Information disclosure via the local system temporary directory (CVE-2021-21290)
• candlepin: netty: Possible request smuggling in HTTP/2 due missing validation (CVE-2021-21295)
• candlepin: netty: Request smuggling via content-length header (CVE-2021-21409)
• tfm-rubygem-sidekiq: XSS via the queue name of the live-poll feature (CVE-2021-30151)
• python-sqlparse: ReDoS via regular expression in StripComments filter (CVE-2021-32839)
• libsolv: various flaws (CVE-2021-33928 CVE-2021-33929 CVE-2021-33930 CVE-2021-33938)
• tfm-rubygem-puma: Inconsistent Interpretation of HTTP Requests in puma (CVE-2021-41136)
• logback-classic: Remote code execution through JNDI call from within its configuration file (CVE-2021-42550)
• candlepin: netty: Control chars in header names may lead to HTTP request smuggling (CVE-2021-43797)
• python-lxml: HTML Cleaner allows crafted and SVG embedded scripts to pass through (CVE-2021-43818)
• python3-django: Potential bypass of an upstream access control based on URL paths (CVE-2021-44420)
• libsolv: Heap overflow (CVE-2021-44568)
• python3-django: Various flaws (CVE-2021-45115 CVE-2021-45116 CVE-2021-45452 CVE-2022-22818)
• tfm-rubygem-actionpack: Information leak between requests (CVE-2022-23633)
• tfm-rubygem-puma: rubygem-rails: Information leak between requests (CVE-2022-23634)
• python3-django: Denial-of-service possibility in file uploads (CVE-2022-23833)
• tfm-rubygem-sidekiq: WebUI Denial of Service caused by number of days on graph (CVE-2022-23837)
• python3-django: Various flaws (CVE-2022-28346 CVE-2022-28347)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

• New repo layout for Satellite, Utils, Maintenance, and Client repos.
• Support for Rocky Linux 9 clients
• Module-based installation on Rocky Linux 8
• Upgrading Satellite Server and Capsule Server installations from Rocky Linux 7 to Rocky Linux 8
• Connected and Disconnected servers supported on Rocky Linux 7 and Rocky Linux 8
• Inter-Server Synchronization improvements
• Puppet integration optional and disabled by default
• Pulp 3 updated to Python 3.8
• Change to Capsule certificate archive
• New default port for communication with Rocky Enterprise Software Foundation Subscription Management * (RHSM) API on Capsule servers
• New Content Views Page (Content Publication workflow simplification)
• New Hosts Page (Technology Preview)
• Registration and preview templates
• Simplified host content source changing
• Improved behavior for configuring and running remote jobs
• Provisioning improvements
• New error signaling unsupported options in TASK-Filter
• Virt-who configuration enhanced to support Nutanix AHV
• Cloud Connector configuration updated
• Improved Insights adoption

The items above are not a complete list of changes. This update also fixes several bugs and adds various enhancements. Documentation for these changes is available from the Release Notes document linked to in the References section.

This update for netty fixes the following issues:

• Updated to version 4.1.75:
  • CVE-2021-37136: Fixed an unrestricted decompressed data size in Bzip2Decoder (bsc#1190610).
  • CVE-2021-37137: Fixed an unrestricted chunk length in SnappyFrameDecoder, which might lead to excessive memory usage (#bsc#1190613).
  • CVE-2021-43797: Fixed a potential HTTP request smuggling issue due to insufficient validation against control characters (bsc#1193672).
  • CVE-2021-21290: Fixed an information disclosure via the local system temporary directory (bsc#1182103).

This update for netty fixes the following issues:

• CVE-2020-11612: The ZlibDecoders allow for unbounded memory allocation while decoding a byte stream (bsc#1168932)
• CVE-2021-21290: Information disclosure via the local system temporary directory (bsc#1182103)
• CVE-2021-37136: Bzip2Decoder doesn't allow setting size restrictions for decompressed data (bsc#1190610)
• CVE-2021-37137: Snappy frame decoder doesn't restrict the chunk length and may buffer skippable chunks (bsc#1190613)

This update for netty fixes the following issues:

• CVE-2020-11612: The ZlibDecoders allow for unbounded memory allocation while decoding a byte stream (bsc#1168932)
• CVE-2021-21290: Information disclosure via the local system temporary directory (bsc#1182103)
• CVE-2021-37136: Bzip2Decoder doesn't allow setting size restrictions for decompressed data (bsc#1190610)
• CVE-2021-37137: Snappy frame decoder doesn't restrict the chunk length and may buffer skippable chunks (bsc#1190613)

This update for netty fixes the following issues:

• CVE-2020-11612: The ZlibDecoders allow for unbounded memory allocation while decoding a byte stream (bsc#1168932)
• CVE-2021-21290: Information disclosure via the local system temporary directory (bsc#1182103)
• CVE-2021-37136: Bzip2Decoder doesn't allow setting size restrictions for decompressed data (bsc#1190610)
• CVE-2021-37137: Snappy frame decoder doesn't restrict the chunk length and may buffer skippable chunks (bsc#1190613)

It was discovered that Netty's Zlib decoders did not limit memory allocations. A remote attacker could possibly use this issue to cause Netty to exhaust memory via malicious input, leading to a denial of service. This issue only affected Ubuntu 16.04 ESM and Ubuntu 20.04 ESM. (CVE-2020-11612)

It was discovered that Netty created temporary files with excessive permissions. A local attacker could possibly use this issue to expose sensitive information. This issue only affected Ubuntu 16.04 ESM, Ubuntu 18.04 ESM, and Ubuntu 20.04 ESM. (CVE-2021-21290)

It was discovered that Netty did not properly validate content-length headers. A remote attacker could possibly use this issue to smuggle requests. This issue was only fixed in Ubuntu 20.04 ESM. (CVE-2021-21295, CVE-2021-21409)

It was discovered that Netty's Bzip2 decompression decoder did not limit the decompressed output data size. A remote attacker could possibly use this issue to cause Netty to exhaust memory via malicious input, leading to a denial of service. This issue only affected Ubuntu 18.04 ESM, Ubuntu 20.04 ESM, Ubuntu 22.04 LTS, and Ubuntu 22.10. (CVE-2021-37136)

It was discovered that Netty's Snappy frame decoder function did not limit chunk lengths. A remote attacker could possibly use this issue to cause Netty to exhaust memory via malicious input, leading to a denial of service. (CVE-2021-37137)

It was discovered that Netty did not properly handle control chars at the beginning and end of header names. A remote attacker could possibly use this issue to smuggle requests. This issue only affected Ubuntu 18.04 ESM, Ubuntu 20.04 ESM, Ubuntu 22.04 LTS, and Ubuntu 22.10. (CVE-2021-43797)

It was discovered that Netty could be made into an infinite recursion when parsing a malformed crafted message. A remote attacker could possibly use this issue to cause Netty to crash, leading to a denial of service. This issue only affected Ubuntu 20.04 ESM, Ubuntu 22.04 LTS, and Ubuntu 22.10. (CVE-2022-41881)

It was discovered that Netty did not validate header values under certain circumstances. A remote attacker could possibly use this issue to perform HTTP response splitting via malicious header values. This issue only affected Ubuntu 18.04 ESM, Ubuntu 20.04 ESM, Ubuntu 22.04 LTS, and Ubuntu 22.10. (CVE-2022-41915)