CVE-2026-47078 Relative path traversal in zip:unzip/zip:extract via check_dir_level depth-counter bypass

Medium 4.8 Published 27 Jul 2026 Updated 24 Sep 2026

Attackers can write files outside the intended directory using crafted zip archives due to a validation bypass in Erlang OTP's zip module.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2026-47078?

CVE-2026-47078 is a medium-severity path traversal vulnerability in Erlang OTP, published on 27 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

Official description

Relative Path Traversal vulnerability in Erlang OTP (stdlib zip module) allows writing files outside the intended extraction directory via a crafted zip archive.

zip:unzip/1,2 and zip:extract/1,2 validate entry paths using zip:check_dir_level/2, which tracks directory depth as a running integer counter: .. decrements it, normal path components increment it. The caller rejects only paths where the final counter value is less than zero. A path such as ../x/y causes the counter to go negative mid-traversal then recover to zero, passing validation while resolving to a location outside the extraction directory when joined with the current working directory via add_cwd.

This vulnerability is associated with program file lib/stdlib/src/zip.erl.

This issue affects OTP from OTP 27.1 before OTP 27.3.4.15, OTP 28.5.0.4, and OTP 29.0.4, corresponding to stdlib from 6.1 before 6.2.2.4, 7.3.0.1, and 8.0.3.

Weakness: CWE-23

Which versions are affected by CVE-2026-47078?

How do I fix CVE-2026-47078?

Upgrade to a fixed version.

Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.

Is CVE-2026-47078 being exploited?

There is no known exploitation of CVE-2026-47078 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2026-47078, EEF-CVE-2026-47078, GHSA-rf72-wp7h-jg3x, UBUNTU-CVE-2026-47078.