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

AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:L/SC:N/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CWE-23

https://cna.erlef.org/cves/CVE-2026-47078.html

https://github.com/erlang/otp/commit/8a933c9c7835b06776d31d17b79b7336627d887a

https://github.com/erlang/otp/security/advisories/GHSA-rf72-wp7h-jg3x

https://osv.dev/vulnerability/EEF-CVE-2026-47078

https://www.erlang.org/doc/system/versions.html#order-of-versions

[{"vendor":"Erlang","product":"OTP","defaultStatus":"unaffected","packageName":"stdlib","cpes":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"modules":["zip"],"programFiles":["src/zip.erl"],"programRoutines":[{"name":"zip:unzip/1"},{"name":"zip:unzip/2"},{"name":"zip:extract/1"},{"name":"zip:extract/2"},{"name":"zip:check_dir_level/2"}],"repo":"https://github.com/erlang/otp","packageURL":"pkg:otp/stdlib?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%20https:%2F%2Fgithub.com%2Ferlang%2Fotp.git","versions":[{"version":"6.1","lessThan":"*","versionType":"otp","status":"affected","changes":[{"at":"8.0.3","status":"unaffected"},{"at":"7.3.0.1","status":"unaffected"},{"at":"6.2.2.4","status":"unaffected"}]}]},{"vendor":"Erlang","product":"OTP","defaultStatus":"unaffected","collectionURL":"https://github.com","packageName":"erlang/otp","cpes":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"modules":["zip"],"programFiles":["lib/stdlib/src/zip.erl"],"programRoutines":[{"name":"zip:unzip/1"},{"name":"zip:unzip/2"},{"name":"zip:extract/1"},{"name":"zip:extract/2"},{"name":"zip:check_dir_level/2"}],"repo":"https://github.com/erlang/otp","packageURL":"pkg:github/erlang/otp","versions":[{"version":"27.1","lessThan":"*","versionType":"otp","status":"affected","changes":[{"at":"29.0.4","status":"unaffected"},{"at":"28.5.0.4","status":"unaffected"},{"at":"27.3.4.15","status":"unaffected"}]},{"version":"8d537f51a4262d24f3395c4148323eaca9facbbd","lessThan":"8a933c9c7835b06776d31d17b79b7336627d887a","versionType":"git","status":"affected"}]}]