RHSA-2026:97456: Moderate: krb5 security update
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: MIT Kerberos 5 (krb5): Denial of Service via integer underflow and out-of-bounds read (CVE-2026-40356) krb5: MIT Kerberos 5: Denial of Service via NULL pointer dereference in NegoEx mechanism (CVE-2026-40355) 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 9 Release Notes linked from the References section.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
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redhat/krb5to a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-debugsourceto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-develto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-libsto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-libs-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-pkinitto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-pkinit-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-serverto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-server-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-server-ldapto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-server-ldap-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-workstationto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-workstation-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-xrealmauthz-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/libkadm5to a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/libkadm5-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9 - Upgrade
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redhat/krb5-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
Upgrade
redhat/krb5-debugsourceto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
Upgrade
redhat/krb5-develto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
Upgrade
redhat/krb5-libsto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
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redhat/krb5-libs-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
Upgrade
redhat/krb5-pkinitto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
Upgrade
redhat/krb5-pkinit-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
Upgrade
redhat/krb5-serverto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
Upgrade
redhat/krb5-server-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
Upgrade
redhat/krb5-server-ldapto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
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redhat/krb5-server-ldap-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
Upgrade
redhat/krb5-workstationto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
Upgrade
redhat/krb5-workstation-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
Upgrade
redhat/krb5-xrealmauthz-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
Upgrade
redhat/libkadm5to a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa - Upgrade
Upgrade
redhat/libkadm5-debuginfoto a version that resolves this vulnerability.Fixed in 1.21.1-10.el9.aa
Event History
Frequently Asked Questions
Which krb5 packages are included in this update?
The advisory lists krb5-debuginfo, krb5-debugsource, krb5-devel, krb5-libs, krb5-libs-debuginfo, krb5-pkinit, krb5-pkinit-debuginfo, and krb5-server.
Does the advisory identify any configuration prerequisites or temporary mitigations?
No. The provided advisory information does not state whether a default configuration is affected, describe exploit prerequisites, or provide a workaround for systems that cannot yet be updated.