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GHSA-269g-pwp5-87pp
No affected components available
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:
- 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.
- 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.
The vulnerability requires local access to the device to be exploited. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker needs basic access or low-level privileges. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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