CVE-2026-21620

Description

Relative Path Traversal, Improper Isolation or Compartmentalization vulnerability in erlang otp erlang/otp (tftp_file modules), erlang otp inets (tftp_file modules), erlang otp tftp (tftp_file modules) allows Relative Path Traversal. This vulnerability is associated with program files lib/tftp/src/tftp_file.erl, src/tftp_file.erl. This issue affects OTP from OTP 17.0 before OTP 28.3.2, OTP 27.3.4.8 and OTP 26.2.5.17, corresponding to tftp from 1.0 before 1.2.4, 1.2.2.1 and 1.1.1.1; also inets from 5.10 before 7.0.

Read the notes from the security team

Why is this CVE low priority?

This requires an application that misuses the tftp API

Learn more about Ubuntu priority

Status

Show unmaintained releases

Package	Ubuntu Release	Status
erlang	26.04 LTS resolute	Fixed 1:27.3.4.6+dfsg-1ubuntu0.2
	25.10 questing	Ignored end of life, was needs-triage
	24.04 LTS noble	Fixed 1:25.3.2.8+dfsg-1ubuntu4.8
	22.04 LTS jammy	Fixed 1:24.2.1+dfsg-1ubuntu0.8
	20.04 LTS focal	Fixed 1:22.2.7+dfsg-1ubuntu0.5+esm3
	18.04 LTS bionic	Fixed 1:20.2.2+dfsg-1ubuntu2+esm4
	16.04 LTS xenial	Fixed 1:18.3-dfsg-1ubuntu3.1+esm4
	14.04 LTS trusty	Fixed 1:16.b.3-dfsg-1ubuntu2.2+esm3

Get expanded security coverage with Ubuntu Pro

Reduce your average CVE exposure time from 98 days to 1 day with expanded CVE patching, ten-years security maintenance and optional support for the full stack of open-source applications. Free for personal use.

Get Ubuntu Pro 30-day free trial

Notes

mdeslaur

Per upstream: "For a system to be vulnerable, the system designer must have used the undescribed {root_dir,RootDir} state as an option under incorrect assumptions. The state value/type is present in the documentation, in a function signature specification, but it is never described. It is only the option's name that may suggest that it could protect against relative path traversal."

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
erlang	Upstream: 696fdec Upstream: 3970738 Upstream: 655fb95

Severity score breakdown

CVSS version: CVSS v4.0

Base score 2.3 · Low

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Attack requirements	Present
Privileges required	Low
User interaction	None
Vulnerable system - Confidentiality impact	Low
Vulnerable system - Integrity impact	Low
Vulnerable system - Availability impact	None
Subsequent system - Confidentiality impact	None
Subsequent system - Integrity impact	None
Subsequent system - Availability impact	None

Scores

Parameter	Value
Base score	2.3 · Low
Base + Threat score	-
Base + Environmental score	-
Base + Threat + Environmental score	-

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N