ssh-agent in OpenSSH before 8.5 has a double free that may be relevant in a few less-common scenarios, such as unconstrained agent-socket access on a legacy operating system, or the forwarding of an agent to an attacker-controlled host.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-28041
• openssh/openssh-portable@e04fd6d
• https://lists.fedoraproject.org/archives/list/[email protected]/message/KQWGII3LQR4AOTPPFXGMTYE7UDEWIUKI/
• https://lists.fedoraproject.org/archives/list/[email protected]/message/TXST2CML2MWY3PNVUXX7FFJE3ATJMNVZ/
• https://security.gentoo.org/glsa/202105-35
• https://security.netapp.com/advisory/ntap-20210416-0002/
• https://www.openssh.com/security.html
• https://www.openssh.com/txt/release-8.5
• https://www.openwall.com/lists/oss-security/2021/03/03/1
• https://www.oracle.com//security-alerts/cpujul2021.html