Red Hat Enterprise Linux authorized_key module authorized_keys _safe_open_write symlink

Summaryinfo

A vulnerability classified as problematic has been found in Red Hat Enterprise Linux. Impacted is the function _safe_open_write of the file authorized_keys of the component authorized_key module. This manipulation causes symlink. The identification of this vulnerability is CVE-2026-126644. The attack can only be executed locally. There is no exploit available.

Detailsinfo

A vulnerability was found in Red Hat Enterprise Linux (version now known). It has been declared as problematic. Affected by this vulnerability is the function _safe_open_write of the file authorized_keys of the component authorized_key module. The manipulation with an unknown input leads to a symlink vulnerability. The CWE definition for the vulnerability is CWE-61. The product, 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 product to operate on unauthorized files. As an impact it is known to affect integrity, and availability. The summary by CVE is:

A link-following flaw was found in the authorized_key module of the ansible.posix collection, residual to the fix for CVE-2026-11837. That fix guards only the final path component (os.chown with follow_symlinks=False and O_NOFOLLOW in _safe_open_write()). When an unprivileged local user replaces their ~/.ssh directory with a symlink to a directory they do not own, and an operator subsequently runs the authorized_key task as root (a common provisioning pattern), the module resolves its path operations through the symlink: atomic_move() writes the temporary file in the symlink target and renames it to <target>/authorized_keys, creating or overwriting a file in the attacker-chosen directory, and os.chmod(sshdir, 0o700) follows the symlink and changes the target directory's permissions. The written file is chowned to the unprivileged user, so this is not a privilege escalation, but it allows an attacker to create or overwrite files (for example in /etc/apt/apt.conf.d/, which APT reads regardless of file ownership) to cause integrity and availability impacts.

The advisory is shared at access.redhat.com. This vulnerability is known as CVE-2026-126644 since 11/11/2026. The exploitation appears to be easy. An attack has to be approached locally. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 11/12/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Operating System

Vendor

• Red Hat

Name

• Enterprise Linux

License

• commercial

Website

• Vendor: https://www.redhat.com/

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