Path traversal in rebar3 via unvalidated dependency app names
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Active
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
rebar3 from 3.7.0-rc1 before 3.27.2 uses the app field of Hex package dependencies as a directory name without validating it. A malicious package publisher can set this field to a relative path, so rebar3 deletes a directory outside the project's _build directory and writes package files there (CWE-22). When a developer runs rebar3 get-deps on a project that depends on such a release, directly or transitively, this happens before the dependency's rebar.config.script is evaluated.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in erlang rebar3 allows a malicious package publisher to delete a directory outside the project's _build directory and extract package files into it when a developer fetches dependencies. A package release's dependencies in a Hex registry carry an app field that names the dependency's OTP application. rebar3 uses this field as the dependency's name without validating it (rebar_packages:parse_deps/1) and builds the dependency's directory from that name (rebar_app_utils:dep_to_app/7). rebar_fetch:download_source_online/2 deletes that directory with rm -rf and moves the fetched package into it. hex.pm didn't restrict the field to a directory name before 2026-10-12, so a publisher could set it to a value such as ../../../../target. When a project depends on such a release directly or transitively, rebar3 get-deps deletes the directory the name resolves to and writes the dependency's files there. This happens before the dependency's own rebar.config.script is evaluated, and get-deps compiles nothing. This issue affects rebar3: from 3.7.0-rc1 before 3.27.2.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
Upgrade rebar3 to 3.27.2, the fixed version listed for this product.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA rebar3 (erlang) Fixed in 3.27.2
Vendor assessments
Timeline
- 2026-10-12 Threatist record created from CVE-2026-103060
- 2026-10-13 Priority changed: MEDIUM → LOW
- 2026-10-16 CISA SSVC decision points changed
- 2026-10-16 Priority changed: LOW → HIGH
- 2026-11-06 Affected versions changed · Red Hat
- 2026-11-06 CVSS score added · Red Hat
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-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
- TI-2026-60474 TLS 1.3 client skips server authentication when ServerHello carries an unsolicited pre_shared_key extension CVSS 4.0CRITICAL 9.3
Sources
- CVE-2026-103060 · CVE Program
- CVE-2026-103060 · NVD
- FIRST EPSS
- CVE-2026-103060 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences