Restrict path segments in TenantIDs (CVE-2021-36156 CVE-2021-36157) #4020
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Updates cortex dependency to prevent paths derived from TenantIDs to become vulnerable to path traversal attacks. CVE-2021-36156 CVE-2021-36157 Signed-off-by: Christian Simon <simon@swine.de>
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What this PR does:
Updates cortex dependency to prevent paths derived from TenantIDs to become vulnerable to path traversal attacks. CVE-2021-36156 CVE-2021-36157
Edit added more details.
An attacker, with suitable access, could trick Loki into sending the contents of files it has access to.
The vulnerability is that the header value
X-Scope-OrgIDis used to construct file paths for rules files, and if crafted to say something like../../sensitive/path/in/deploymentthen Loki will attempt to parse a rules file at that location and include some of the contents in the error message.Other Loki API requests can also be sent a malicious OrgID header, e.g. tricking the ingester into writing metrics to a different location, but the effect is nuisance rather than disclosure.
Mitigations:
If you have a proxy in front of Loki that supplies the OrgID header, so it cannot be crafted by an attacker, then you are not vulnerable. We always recommend such a proxy
If you run Loki with limited access to sensitive files, e.g. in a container or chroot, and as a user with limited access, then this will constrain the vulnerability to that access.