RHSA-2021:1593 - Security Advisory

Topic

An update for krb5 is now available for Red Hat Enterprise Linux 8.

Red Hat Product Security has rated this update as having a security impact of Moderate. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

Kerberos is a network authentication system, which can improve the security of your network by eliminating the insecure practice of sending passwords over the network in unencrypted form. It allows clients and servers to authenticate to each other with the help of a trusted third party, the Kerberos key distribution center (KDC).

Security Fix(es):

• krb5: unbounded recursion via an ASN.1-encoded Kerberos message in lib/krb5/asn.1/asn1_encode.c may lead to DoS (CVE-2020-28196)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the Red Hat Enterprise Linux 8.4 Release Notes linked from the References section.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing the updated packages, running Kerberos services (krb5kdc, kadmin, and kprop) will be restarted automatically.

Affected Products

• Red Hat Enterprise Linux for x86_64 8 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 8.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 8.4 x86_64
• Red Hat Enterprise Linux Server - AUS 8.6 x86_64
• Red Hat Enterprise Linux Server - AUS 8.4 x86_64
• Red Hat Enterprise Linux for IBM z Systems 8 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 8.6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 8.4 s390x
• Red Hat Enterprise Linux for Power, little endian 8 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 8.6 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 8.4 ppc64le
• Red Hat Enterprise Linux Server - TUS 8.6 x86_64
• Red Hat Enterprise Linux Server - TUS 8.4 x86_64
• Red Hat Enterprise Linux for ARM 64 8 aarch64
• Red Hat Enterprise Linux for ARM 64 - Extended Update Support 8.6 aarch64
• Red Hat Enterprise Linux for ARM 64 - Extended Update Support 8.4 aarch64
• Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 8.6 ppc64le
• Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 8.4 ppc64le
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 8.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 8.4 x86_64

Fixes

• BZ - 1835713 - krb5: typo error(s) in man page(s)
• BZ - 1868039 - krb5 spec file - wrong url in source0 and source1
• BZ - 1869055 - [doc] kvno usage not compliant with man page kvno(1)
• BZ - 1872689 - Radius Authentication does not work in FIPS mode
• BZ - 1901041 - CVE-2020-28196 krb5: unbounded recursion via an ASN.1-encoded Kerberos message in lib/krb5/asn.1/asn1_encode.c may lead to DoS

CVEs

• CVE-2020-28196

References

• https://access.redhat.com/security/updates/classification/#moderate
• https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/8.4_release_notes/