Relative Path Traversal in otp - CVE-2026-21620
Published: April 10, 2026
Vulnerability identifier: #VU125772
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-21620
CWE-ID: CWE-23
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: erlang
Affected software:
otp
otp
Detailed vulnerability description
The vulnerability allows a remote user to read and write arbitrary files.
The vulnerability exists due to relative path traversal in the Erlang/OTP TFTP server when handling remote file requests with ../ path components while using the undocumented root_dir option. A remote user can send crafted file requests to read and write arbitrary files.
Exploitation requires that the system designer used the undocumented {root_dir,RootDir} option under incorrect assumptions and that the service is reachable from untrusted hosts.
How to mitigate CVE-2026-21620
Install security update from vendor's website.