Go os Root symlink traversal before 1.27 (v1.25.12 & 1.26 <1.26.5)
CVE-2026-39822 Published on July 8, 2026
Root escape via symlink plus trailing slash in os
On Unix systems, opening a file in an os.Root improperly follows symlinks to locations outside of the Root when the final path component of the a path is a symbolic link and the path ends in /. For example, 'root.Open("symlink/")' will open "symlink" even when "symlink" is a symbolic link pointing outside of the root.
Vulnerability Analysis
CVE-2026-39822 is exploitable with local system access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
What is a Symlink following Vulnerability?
The software, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the software to operate on unauthorized files. A software system that allows UNIX symbolic links (symlink) as part of paths whether in internal code or through user input can allow an attacker to spoof the symbolic link and traverse the file system to unintended locations or access arbitrary files. The symbolic link can permit an attacker to read/write/corrupt a file that they originally did not have permissions to access.
CVE-2026-39822 has been classified to as a Symlink following vulnerability or weakness.
Products Associated with CVE-2026-39822
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Affected Versions
Go standard library os:- Before 1.25.12 is affected.
- Version 1.26.0-0 and below 1.26.5 is affected.
- Version 1.27.0-0 and below 1.27.0-rc.2 is affected.