How severe is CVE-2026-39973?

CVE-2026-39973 has a CVSS score of 7.1/10, rated HIGH. Immediate patching is strongly recommended.

Which products are affected by CVE-2026-39973?

Affected package information for CVE-2026-39973 is not yet fully mapped. Check the official advisory links for details.

How do I patch CVE-2026-39973?

Apply the apktool apktool security patch or hotfix for CVE-2026-39973 on the affected version, following the vendor advisory for your exact build.

How do I detect CVE-2026-39973 across my infrastructure?

Inventory every apktool apktool deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for remote code execution at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.

How do I mitigate CVE-2026-39973 if there is no patch (or I can't update yet)?

Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.

How does O3 Security protect against CVE-2026-39973?

O3 detects and blocks CVE-2026-39973 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Is CVE-2026-39973 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-39973 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-39973?

CVE-2026-39973 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 8th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-39973?

CVE-2026-39973 is classified as Path Traversal (CWE-22). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

Which products and versions are affected by CVE-2026-39973?

CVE-2026-39973 affects apktool apktool. Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2026-39973 published, and has it been updated?

CVE-2026-39973 was published on April 21, 2026 and was last updated on June 17, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2026-39973

HIGH

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…

Published

Apr 21, 2026

Updated

Jun 17, 2026

Affected

0 pkgs

Patched

None yet

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk8th percentile+0.18%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

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.

Affected Products

1 product · 1 configurations

Application

apktoolapktool

≥ 3.0.0 && < 3.0.2

range

Detection & mitigation playbook

Vendor / appliance

Detect
Inventory every apktool apktool deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for remote code execution at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Fix
Apply the apktool apktool security patch or hotfix for CVE-2026-39973 on the affected version, following the vendor advisory for your exact build.
Workarounds
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2026-39973 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Tailored to CVE-2026-39973. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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 dir

O3 Security · Runtime Protection

Is CVE-2026-39973 being exploited in your environment?

O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2026-39973 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.

Protect my workloads How runtime protection works