Relative path traversal in zip:unzip/zip:extract via check_dir_level depth-counter bypass
Key facts
- Attack vector
- Local
- Privileges required
- None
- User interaction
- Passive
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · Low
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 4 products
- Red Hat Hardened Images
- Red Hat OpenStack Platform 16.2
- Red Hat OpenStack Platform 17.1
- Red Hat OpenStack Platform 18.0
Timeline
- 2026-10-02 Threatist record created from CVE-2026-47078
References
More Erlang vulnerabilities
- TI-2025-23504 Erlang/OTP SSH Vulnerable to Pre-Authentication RCE KEVCVSS 3.1CRITICAL 10.0
- TI-2026-48954 httpd parks a request worker indefinitely on a malformed chunk size sent after the headers CVSS 4.0HIGH 8.7
- TI-2023-26623 The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6… CVSS 3.1MEDIUM 5.9
- TI-2026-71037 Path traversal in rebar3 via unvalidated dependency app names CVSS 4.0HIGH 7.5
- TI-2024-36042 ssl fails to validate incorrect extened key usage CVSS 3.1MEDIUM 5.5
- TI-2020-10791 Rebar3 versions 3.0.0-beta.3 to 3.13.2 are vulnerable to OS command injection via URL… CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-47078 · CVE Program
- CVE-2026-47078 · NVD
- FIRST EPSS
- CVE-2026-47078 · Red Hat security data · CC BY 4.0
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