Summary
Partial Path Traversal in com.amazonaws:aws-java-sdk-s3
Overview
A partial-path traversal issue exists within the downloadDirectory method in the AWS S3 TransferManager component of the AWS SDK for Java v1. Applications using the SDK control the destinationDirectory argument, but S3 object keys are determined by the application that uploaded the objects. The downloadDirectory method allows the caller to pass a filesystem object in the object key but contained an issue in the validation logic for the key name. A knowledgeable actor could bypass the validation logic by including a UNIX double-dot in the bucket key. Under certain conditions, this could permit them to retrieve a directory from their S3 bucket that is one level up in the filesystem from their working directory.
This issue’s scope is limited to directories whose name prefix matches the destinationDirectory. E.g. for destination directory/tmp/foo, the actor can cause a download to /tmp/foo-bar, but not /tmp/bar.
Versions of the AWS Java SDK for S3 v1 before and including v1.12.260 are affected by this issue.
Root Cause
The com.amazonaws.services.s3.transfer.TransferManager::downloadDirectory contains a partial-path traversal vulnerability.
This is due to the guard logic in leavesRoot containing an insufficient protection against partial-path traversal.
The application controls the localBaseDirectory argument, but the key comes from the AWS bucket entry (ie. can be attacker controlled). The above bit of logic can be bypassed with the following payloads:
// The following will return 'false', although the attacker value will "leave" the `/usr/foo` directory
leavesRoot(new File("/usr/foo"), "/../foo-bar/bar")
This guard is used here which should guard against path traversal, however leavesRoot is an insufficient guard:
True Root cause
If the result of parent.getCanonicalPath() is not slash terminated it allows for partial path traversal.
Consider "/usr/outnot".startsWith("/usr/out"). The check is bypassed although outnot is not under the out directory.
The terminating slash may be removed in various places. On Linux println(new File("/var/")) returns /var, but println(new File("/var", "/")) - /var/, however println(new File("/var", "/").getCanonicalPath()) - /var.
- @JarLob (Jaroslav Lobačevski)
Workarounds
When calling com.amazonaws.services.s3.transfer.TransferManager::downloadDirectory pass a KeyFilter that forbids S3ObjectSummary objects that getKey method return a string containing the substring .. .
References
Similar vulnerabilities:
- ESAPI (The OWASP Enterprise Security API) - https://nvd.nist.gov/vuln/detail/CVE-2022-23457
For more information
If you have any questions or comments about this advisory, please contact AWS's Security team.
Impact
If com.amazonaws.services.s3.transfer.TransferManager::downloadDirectory is used to download an untrusted buckets contents, the contents of that bucket can be written outside of the intended destination directory.
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
CVE-2022-31159 has a CVSS score of 7.9 (High). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.12.261); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Upgrade to the AWS SDK for Java >= 1.12.261, if you are on a version < 1.12.261.
Frequently Asked Questions
- What is CVE-2022-31159? CVE-2022-31159 is a high-severity path traversal vulnerability in com.amazonaws:aws-java-sdk-s3 (maven), affecting versions < 1.12.261. It is fixed in 1.12.261. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
- How severe is CVE-2022-31159? CVE-2022-31159 has a CVSS score of 7.9 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of com.amazonaws:aws-java-sdk-s3 are affected by CVE-2022-31159? com.amazonaws:aws-java-sdk-s3 (maven) versions < 1.12.261 is affected.
- Is there a fix for CVE-2022-31159? Yes. CVE-2022-31159 is fixed in 1.12.261. Upgrade to this version or later.
- Is CVE-2022-31159 exploitable, and should I be worried? Whether CVE-2022-31159 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2022-31159 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2022-31159? Upgrade
com.amazonaws:aws-java-sdk-s3to 1.12.261 or later.