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NLnet Labs Unbound, up to and including version 1.12.0,...

Moderate severity Unreviewed Published May 24, 2022 to the GitHub Advisory Database • Updated Mar 29, 2023

Package

No package listedSuggest a package

Affected versions

Unknown

Patched versions

Unknown

Description

NLnet Labs Unbound, up to and including version 1.12.0, and NLnet Labs NSD, up to and including version 4.3.3, contain a local vulnerability that would allow for a local symlink attack. When writing the PID file, Unbound and NSD create the file if it is not there, or open an existing file for writing. In case the file was already present, they would follow symlinks if the file happened to be a symlink instead of a regular file. An additional chown of the file would then take place after it was written, making the user Unbound/NSD is supposed to run as the new owner of the file. If an attacker has local access to the user Unbound/NSD runs as, she could create a symlink in place of the PID file pointing to a file that she would like to erase. If then Unbound/NSD is killed and the PID file is not cleared, upon restarting with root privileges, Unbound/NSD will rewrite any file pointed at by the symlink. This is a local vulnerability that could create a Denial of Service of the system Unbound/NSD is running on. It requires an attacker having access to the limited permission user Unbound/NSD runs as and point through the symlink to a critical file on the system.

References

Published by the National Vulnerability Database Dec 7, 2020
Published to the GitHub Advisory Database May 24, 2022
Last updated Mar 29, 2023

Severity

Moderate
5.5
/ 10

CVSS base metrics

Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weaknesses

CVE ID

CVE-2020-28935

GHSA ID

GHSA-q92f-7cwj-w4w5

Source code

No known source code

Dependabot alerts are not supported on this advisory because it does not have a package from a supported ecosystem with an affected and fixed version.

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