CVE-2020-15250

In JUnit4 from version 4.7 and before 4.13.1, the test rule TemporaryFolder contains a local information disclosure vulnerability. On Unix like systems, the system's temporary directory is shared between all users on that system. Because of this, when files and directories are written into this directory they are, by default, readable by other users on that same system. This vulnerability does not allow other users to overwrite the contents of these directories or files. This is purely an information disclosure vulnerability. This vulnerability impacts you if the JUnit tests write sensitive information, like API keys or passwords, into the temporary folder, and the JUnit tests execute in an environment where the OS has other untrusted users. Because certain JDK file system APIs were only added in JDK 1.7, this this fix is dependent upon the version of the JDK you are using. For Java 1.7 and higher users: this vulnerability is fixed in 4.13.1. For Java 1.6 and lower users: no patch is available, you must use the workaround below. If you are unable to patch, or are stuck running on Java 1.6, specifying the java.io.tmpdir system environment variable to a directory that is exclusively owned by the executing user will fix this vulnerability. For more information, including an example of vulnerable code, see the referenced GitHub Security Advisory.

In JUnit4 from version 4.7 and before 4.13.1, the test rule TemporaryFolder contains a local information disclosure vulnerability. On Unix like systems, the system's temporary directory is shared between all users on that system. Because of this, when files and directories are written into this directory they are, by default, readable by other users on that same system. This vulnerability does not allow other users to overwrite the contents of these directories or files. This is purely an information disclosure vulnerability. This vulnerability impacts you if the JUnit tests write sensitive information, like API keys or passwords, into the temporary folder, and the JUnit tests execute in an environment where the OS has other untrusted users. Because certain JDK file system APIs were only added in JDK 1.7, this this fix is dependent upon the version of the JDK you are using. For Java 1.7 and higher users: this vulnerability is fixed in 4.13.1. For Java 1.6 and lower users: no patch is available, you must use the workaround below. If you are unable to patch, or are stuck running on Java 1.6, specifying the java.io.tmpdir system environment variable to a directory that is exclusively owned by the executing user will fix this vulnerability. For more information, including an example of vulnerable code, see the referenced GitHub Security Advisory.

Vulnerability

The JUnit4 test rule TemporaryFolder contains a local information disclosure vulnerability.

Example of vulnerable code:

public static class HasTempFolder {
    @Rule
    public TemporaryFolder folder = new TemporaryFolder();

    @Test
    public void testUsingTempFolder() throws IOException {
        folder.getRoot(); // Previous file permissions: `drwxr-xr-x`; After fix:`drwx------`
        File createdFile= folder.newFile("myfile.txt"); // unchanged/irrelevant file permissions
        File createdFolder= folder.newFolder("subfolder"); // unchanged/irrelevant file permissions
        // ...
    }
}

Impact

On Unix like systems, the system's temporary directory is shared between all users on that system. Because of this, when files and directories are written into this directory they are, by default, readable by other users on that same system.

This vulnerability does not allow other users to overwrite the contents of these directories or files. This is purely an information disclosure vulnerability.

When analyzing the impact of this vulnerability, here are the important questions to ask:

1. Do the JUnit tests write sensitive information, like API keys or passwords, into the temporary folder?
   • If yes, this vulnerability impacts you, but only if you also answer 'yes' to question 2.
   • If no, this vulnerability does not impact you.
2. Do the JUnit tests ever execute in an environment where the OS has other untrusted users. This may apply in CI/CD environments but normally won't be 'yes' for personal developer machines.
   • If yes, and you answered 'yes' to question 1, this vulnerability impacts you.
   • If no, this vulnerability does not impact you.

Patches

Because certain JDK file system APIs were only added in JDK 1.7, this this fix is dependent upon the version of the JDK you are using.

• Java 1.7 and higher users: this vulnerability is fixed in 4.13.1.
• Java 1.6 and lower users: no patch is available, you must use the workaround below.

Workarounds

If you are unable to patch, or are stuck running on Java 1.6, specifying the java.io.tmpdir system environment variable to a directory that is exclusively owned by the executing user will fix this vulnerability.

References

• CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
• Fix commit https://github.com/junit-team/junit4/commit/610155b8c22138329f0723eec22521627dbc52ae

Similar Vulnerabilities

• 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, please pen an issue in junit-team/junit4.

JUnit is a simple framework to write repeatable tests. It is an instance of the xUnit architecture for unit testing frameworks.

Security Fix(es):

In JUnit4 from version 4.7 and before 4.13.1, the test rule TemporaryFolder contains a local information disclosure vulnerability. On Unix like systems, the system's temporary directory is shared between all users on that system. Because of this, when files and directories are written into this directory they are, by default, readable by other users on that same system. This vulnerability does not allow other users to overwrite the contents of these directories or files. This is purely an information disclosure vulnerability. This vulnerability impacts you if the JUnit tests write sensitive information, like API keys or passwords, into the temporary folder, and the JUnit tests execute in an environment where the OS has other untrusted users. Because certain JDK file system APIs were only added in JDK 1.7, this this fix is dependent upon the version of the JDK you are using. For Java 1.7 and higher users: this vulnerability is fixed in 4.13.1. For Java 1.6 and lower users: no patch is available, you must use the workaround below. If you are unable to patch, or are stuck running on Java 1.6, specifying the java.io.tmpdir system environment variable to a directory that is exclusively owned by the executing user will fix this vulnerability. For more information, including an example of vulnerable code, see the referenced GitHub Security Advisory.(CVE-2020-15250)

Red Hat Lightwell has released junit:junit 4.12.0.rhlw-00002 with a backported security fix.

CVE-2020-15250: In JUnit4 from version 4.7 and before 4.13.1, the test rule TemporaryFolder contains a local information disclosure vulnerability. On Unix like systems, the system's temporary directory is shared between all users on that system. Because of this, when files and directories are written into this directory they are, by default, readable by other users on that same system. This vulnerability does not allow other users to overwrite the contents of these directories or files. This is purely an information disclosure vulnerability. This vulnerability impacts you if the JUnit tests write sensitive information, like API keys or passwords, into the temporary folder, and the JUnit tests execute in an environment where the OS has other untrusted users. Because certain JDK file system APIs were only added in JDK 1.7, this this fix is dependent upon the version of the JDK you are using. For Java 1.7 and higher users: this vulnerability is fixed in 4.13.1. For Java 1.6 and lower users: no patch is available, you must use the workaround below. If you are unable to patch, or are stuck running on Java 1.6, specifying the java.io.tmpdir system environment variable to a directory that is exclusively owned by the executing user will fix this vulnerability. For more information, including an example of vulnerable code, see the referenced GitHub Security Advisory.

This patched artifact is a drop-in replacement for junit:junit 4.12.0 from Maven Central.

Red Hat Lightwell has released junit:junit 4.13.0.rhlw-00001 with a backported security fix.

CVE-2020-15250: In JUnit4 from version 4.7 and before 4.13.1, the test rule TemporaryFolder contains a local information disclosure vulnerability. On Unix like systems, the system's temporary directory is shared between all users on that system. Because of this, when files and directories are written into this directory they are, by default, readable by other users on that same system. This vulnerability does not allow other users to overwrite the contents of these directories or files. This is purely an information disclosure vulnerability. This vulnerability impacts you if the JUnit tests write sensitive information, like API keys or passwords, into the temporary folder, and the JUnit tests execute in an environment where the OS has other untrusted users. Because certain JDK file system APIs were only added in JDK 1.7, this this fix is dependent upon the version of the JDK you are using. For Java 1.7 and higher users: this vulnerability is fixed in 4.13.1. For Java 1.6 and lower users: no patch is available, you must use the workaround below. If you are unable to patch, or are stuck running on Java 1.6, specifying the java.io.tmpdir system environment variable to a directory that is exclusively owned by the executing user will fix this vulnerability. For more information, including an example of vulnerable code, see the referenced GitHub Security Advisory.

This patched artifact is a drop-in replacement for junit:junit 4.13.0 from Maven Central.

In JUnit4 from version 4.7 and before 4.13.1, the test rule TemporaryFolder contains a local information disclosure vulnerability. On Unix like systems, the system's temporary directory is shared between all users on that system. Because of this, when files and directories are written into this directory they are, by default, readable by other users on that same system. This vulnerability does not allow other users to overwrite the contents of these directories or files. This is purely an information disclosure vulnerability. This vulnerability impacts you if the JUnit tests write sensitive information, like API keys or passwords, into the temporary folder, and the JUnit tests execute in an environment where the OS has other untrusted users. Because certain JDK file system APIs were only added in JDK 1.7, this this fix is dependent upon the version of the JDK you are using. For Java 1.7 and higher users: this vulnerability is fixed in 4.13.1. For Java 1.6 and lower users: no patch is available, you must use the workaround below. If you are unable to patch, or are stuck running on Java 1.6, specifying the java.io.tmpdir system environment variable to a directory that is exclusively owned by the executing user will fix this vulnerability. For more information, including an example of vulnerable code, see the referenced GitHub Security Advisory.

TuxCare rebuilt junit:junit to address 1 CVE. Fixed in 4.13-tuxcare.1.

TuxCare rebuilt junit:junit to address 1 CVE. Fixed in 4.12-tuxcare.1.

It was discovered that junit contained a local information disclosure vulnerability. On Unix like systems, the system's temporary directory is shared between all users on that system. Because of this, when files and directories are written into this directory they are, by default, readable by other users on that same system. This vulnerability does not allow other users to overwrite the contents of these directories or files. This is purely an information disclosure vulnerability (CVE-2020-15250).

It was discovered that JUnit 4 contains a local information disclosure vulnerability. An attacker could possibly use this issue to obtain sensitive information.