The Alertmanager in CNCF Cortex before 1.8.1 has a local file disclosure vulnerability when -experimental.alertmanager.enable-api is used. The HTTP basic auth password_file can be used as an attack vector to send any file content via a webhook. The alertmanager templates can be used as an attack vector to send any file content because the alertmanager can load any text file specified in the templates list.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-31232
• https://github.com/cortexproject/cortex/pull/4129/files
• https://community.grafana.com/c/security-announcements
• https://github.com/cortexproject/cortex
• https://lists.cncf.io/g/cortex-users/message/50