Bug 2507547 (CVE-2026-47078)

Summary: CVE-2026-47078 otp: Erlang OTP: Arbitrary file write via relative path traversal in zip module
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: eglynn, jjoyce, jpretori, jschluet, lhh, mburns, mgarciac
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Erlang OTP stdlib zip module. The zip:unzip and zip:extract functions, which handle archive extraction, are vulnerable to a relative path traversal attack. A remote attacker could craft a malicious zip archive containing specially formed entry names. When processed, this could allow the attacker to write arbitrary files outside the intended extraction directory, potentially leading to remote code execution or data corruption.
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Description OSIDB Bzimport 2026-07-27 16:01:37 UTC 
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 27.3.4.15, 28.5.0.4, and 29.0.4 corresponding to stdlib from 6.1 before 6.2.2.4, 7.3.0.1, and 8.0.3.