iBotPeaches Apktool up to 3.0.1 APK File ResFileDecoder.java BrutIO.sanitizePath path traversal

Summaryinfo

A vulnerability categorized as critical has been discovered in iBotPeaches Apktool up to 3.0.1. Affected by this vulnerability is the function BrutIO.sanitizePath in the library brut/androlib/res/decoder/ResFileDecoder.java of the component APK File Handler. The manipulation results in path traversal. This vulnerability is known as CVE-2026-39973. Attacking locally is a requirement. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in iBotPeaches Apktool up to 3.0.1. Affected is the function BrutIO.sanitizePath in the library brut/androlib/res/decoder/ResFileDecoder.java of the component APK File Handler. The manipulation with an unknown input leads to a path traversal vulnerability. CWE is classifying the issue as CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Apktool is a tool for reverse engineering Android APK files. In versions 3.0.0 and 3.0.1, a path traversal vulnerability in `brut/androlib/res/decoder/ResFileDecoder.java` allows a maliciously crafted APK to write arbitrary files to the filesystem during standard decoding (`apktool d`). This is a security regression introduced in commit e10a045 (PR #4041, December 12, 2025), which removed the `BrutIO.sanitizePath()` call that previously prevented path traversal in resource file output paths. An attacker can embed `../` sequences in the `resources.arsc` Type String Pool to escape the output directory and write files to arbitrary locations, including `~/.ssh/config`, `~/.bashrc`, or Windows Startup folders, escalating to RCE. The fix in version 3.0.2 re-introduces `BrutIO.sanitizePath()` in `ResFileDecoder.java` before file write operations.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-39973 since 04/08/2026. The exploitability is told to be easy. The attack needs to be approached locally. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1006.

Upgrading to version 3.0.2 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch e10a0450c7afcd9462c0b76bcbff0e7428b92bdd is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-24043). Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• iBotPeaches

Name

• Apktool

Version

• 3.0.0
• 3.0.1

License

• open-source

Website

• Product: https://github.com/iBotPeaches/Apktool/

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Once again VulDB remains the best source for vulnerability data.

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