Security Bulletin: This Power System update is being released to address CVE 2021-29891

Summary

POWER9: In response to a security issue with BMC’s HTTPS server, a new Power System firmware update is being released to address Common Vulnerabilities and Exposures issue number CVE 2021-29891.

Vulnerability Details

CVEID:CVE-2021-29891
**DESCRIPTION:**IBM OPENBMC could allow a privileged user to upload an improper site identity certificate that may cause it to lose network services.
CVSS Base score: 4.9
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/207221 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H)

Affected Products and Versions

Remediation/Fixes

Customers with the products below running OP910, there is no Power System firmware update for this. Please follow the Workarounds and Mitigations steps:

1. IBM Power System AC922 (8335-GTG)

Customers with the products below running OP920, OP930, or OP940, install OP940.30:

1. IBM Power System AC922 (8335-GTH, 8335-GTX)

Customers with the products below running OP940, install OP940.30:

1. IBM Hardware Management Console (HMC) System Firmware (7063-CR2)

Workarounds and Mitigations

To avoid this problem, ensure uploaded certificates use a strong key: RSA key at least 1024 bits and ECC key at least 160 bits.

To recover from this problem, login to the BMC’s command shell with the root account (for example, via SSH access), and use that access to delete the improper certificate and restart the web server. The server will then start with a self-signed certificate. You may then replace the certificate.

On a system running OP920 or OP930, use the following commands:
rm /etc/ssl/certs/nginx/cert.pem
systemctl restart nginx

On a system running OP940, use the following commands:
rm /etc/ssl/certs/https/server.pem
systemctl restart bmcweb