CVE-2026-47078

01/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.

02/References6

• cna.erlef.org/cves/CVE-2026-47078.html
• github.com/erlang/otp/commit/8a933c9c7835b06776d31d17b79b733662…
• github.com/erlang/otp/commit/8d537f51a4262d24f3395c4148323eaca9…
• github.com/erlang/otp/security/advisories/GHSA-rf72-wp7h-jg3x
• osv.dev/vulnerability/EEF-CVE-2026-47078
• www.erlang.org/doc/system/versions.html#order-of-versions