CVE-2021-41617

Published: 26 September 2021

sshd in OpenSSH 6.2 through 8.x before 8.8, when certain non-default configurations are used, allows privilege escalation because supplemental groups are not initialized as expected. Helper programs for AuthorizedKeysCommand and AuthorizedPrincipalsCommand may run with privileges associated with group memberships of the sshd process, if the configuration specifies running the command as a different user.

Notes

openssh-ssh1 is provided for compatibility with old devices that
cannot be upgraded to modern protocols. Thus we may not provide security
support for this package if doing so would prevent access to equipment.

Only applies to non-default configurations where
AuthorizedKeysCommand or AuthorizedPrincipalsCommand are used.

Cannot reproduce since sshd for all releases drops supplementary
groups early when it starts with setgroups(0, NULL).

Status

Severity score breakdown

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-41617
• https://www.openwall.com/lists/oss-security/2021/09/26/1
• https://www.openssh.com/txt/release-8.8
• https://www.openssh.com/security.html
• https://ubuntu.com/security/notices/USN-5666-1
• NVD
• Launchpad
• Debian

Bugs

• http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=995130
• https://bugzilla.suse.com/show_bug.cgi?id=1190975