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Message-ID: <ac7affe1-a181-42ca-810b-d58d7fa4f5dc@oracle.com>
Date: Mon, 9 Nov 2026 15:54:42 -0800
From: Alan Coopersmith <alan.coopersmith@...cle.com>
To: oss-security@...ts.openwall.com
Subject: krb5-1.22.3 is released, with fixes for 21 CVEs
https://mailman.mit.edu/pipermail/kerberos-announce/2026q4/000212.html announces:
> The MIT Kerberos Team announces the availability of MIT Kerberos 5
> Release 1.22.3. Please see below for a list of some major changes
> included, or consult the README file in the source tree for a more
> detailed list of significant changes.
>
> RETRIEVING KERBEROS 5 RELEASE 1.22.3
> ====================================
>
> You may retrieve the Kerberos 5 Release 1.22.3 source from the
> following URL:
>
> https://kerberos.org/dist/
>
> The homepage for the krb5-1.22.3 release is:
>
> https://web.mit.edu/kerberos/krb5-1.23/
>
> Further information about Kerberos 5 may be found at the following
> URL:
>
> https://web.mit.edu/kerberos/
>
> and at the MIT Kerberos Consortium web site:
>
> https://www.kerberos.org/
>
>
> Major changes in 1.22.3 (2026-11-09)
> ====================================
>
> This is a bug fix release, with a focus on security issues discovered
> with the aid of large language models. See
> https://web.mit.edu/kerberos/advisories/MITKRB5-SA-2026-001.txt for
> information on the risks of continuing to use unpatched releases.
>
> * Fix a logic error when checking PAC server checksums
> [CVE-2026-111423].
>
> * Check for unkeyed checksums when validating CAMMAC verifiers
> [CVE-2026-71199].
>
> * Fix a loophole in the KDC's client authdata filtering which could
> allow clients to include fake PAC and CAMMAC authdata values when
> requesting service tickets. These fake values would be rejected by
> application servers, were it not for the two bugs noted above.
>
> * Check for the lockdown_keys attribute when processing password
> change protocol requests in kadmind [CVE-2026-107884].
>
> * In libgssrpc, when processing RPC messages using the RPCSEC_GSS
> flavor, use the verified service type included in the RPC request to
> determine how to unwrap arguments and wrap return values, instead of
> the unverified service type included during authentication
> [CVE-2026-118380].
>
> * In libgssrpc, disable the AUTH_GSSAPI server auth flavor unless the
> "GSSRPC_ALLOW_AUTH_GSSAPI" environment variable is set. AUTH_GSSAPI
> is only needed for very old (pre-1.4) clients [CVE-2026-112322]
> [CVE-2026-112323].
>
> * Fix numerous null pointer deferences, read overruns, unbounded
> memory allocations, and memory leaks that could be used as denial of
> service attacks against the KDC, kadmind, application servers, or
> client programs [CVE-2026-40355] [CVE-2026-40356] [CVE-2026-71200]
> [CVE-2026-107364] [CVE-2026-107708] [CVE-2026-107778]
> [CVE-2026-112314] [CVE-2026-112315] [CVE-2026-112316]
> [CVE-2026-112317] [CVE-2026-112318] [CVE-2026-112319]
> [CVE-2026-112320] [CVE-2026-112321] [CVE-2026-112323]
> [CVE-2026-119079].
>
> * Fix a client crash when a KKDCP proxy daemon closes the TLS session
> without supplying any response data.
>
> * Shut down kpropd gracefully when a termination signal is received,
> when operating in incremental propagation mode.
>
> * Detect when an incremental propagation update is applied to a
> nonexistent principal; when this happens, force a full resync
> instead of crashing.
>
> * Fix a KDC crash when the LDAP KDB module loses its connection to the
> LDAP server.
>
> * Avoid a crash on macOS when the native API ccache type is used
> before and after forking a process.
>
> * When an application accepts a GSS context without asking for
> delegated credentials, discard any credentials sent by the initiator
> without parsing them first.
>
> * On Windows, prevent buffer overflows when the KDC sends an
> unexpectedly long prompt string via OTP preauthentication.
>
> * On Windows, move the default per-machine krb5.ini location from
> C:\ProgramData\MIT\Kerberos to C:\Program Files\MIT\Kerberos5, as
> the former location could be pre-created by an unutrusted user
> before KfW installation.
>
> * On Windows, add error checking to kfwlogon to ensure that it does
> not set ACLs on a cache file it did not create.
>
> * On Windows, prevent several buffer overflows that could occur if an
> application passes a large principal name to leashdll APIs.
>
> * On Windows, prevent buffer overflows when the LSA cache contains
> credentials with long principal name components.
https://web.mit.edu/kerberos/advisories/MITKRB5-SA-2026-001.txt advises:
> MITKRB5-SA-2026-001
>
> MIT krb5 Security Advisory 2026-001
> Original release: 2026-11-09
> Last update: 2026-11-09
>
> Topic: Multiple vulnerabilities fixed in patch 1.22.3
>
> SUMMARY
> =======
>
> Like many open source projects, MIT krb5 has faced greatly increased
> scrutiny over the past few months from researchers employing large
> language models. As a result, release 1.22.3 fixes many more
> vulnerabilities than a typical MIT krb5 patch release. This advisory
> discusses the combined impact of those vulnerabilities on unpatched
> components.
>
> AUTHORIZATION BYPASS ATTACKS
> ============================
>
> An authenticated attacker can bypass authentication indicator
> enforcement by requesting a service ticket with fake CAMMAC
> authorization data. Updating to the 1.22.3 release on the KDC is
> sufficient to prevent this attack.
>
> An authenticated attacker can bypass an application server's PAC
> authorization data checks by requesting a service ticket with a fake
> PAC. Updating to the 1.22.3 release on either the KDC or the affected
> application server will prevent this attack.
>
> An authenticated attacker with administrative privileges can bypass
> the lockdown_keys attribute by using the password change protocol
> instead of the kadmin protocol to modify a principal's keys.
>
> The CVEs in this category include:
>
> CVE-2026-71199
> CVE-2026-107884
> CVE-2026-111423
>
>
> DENIAL OF SERVICE ATTACKS
> =========================
>
> The KDC, kadmind, and GSS-API application servers are all vulnerable
> to denial of service attacks by unauthenticated attackers. The CVEs
> in this category include:
>
> CVE-2026-40355
> CVE-2026-40356
> CVE-2026-71200
> CVE-2026-107364
> CVE-2026-107708
> CVE-2026-107778
> CVE-2026-112314
> CVE-2026-112315
> CVE-2026-112316
> CVE-2026-112317
> CVE-2026-112318
> CVE-2026-112319
> CVE-2026-112320
> CVE-2026-112321
> CVE-2026-112322
> CVE-2026-112323
> CVE-2026-119079
>
>
> GSS-RPC USE OF UNVERIFIED SERVICE TYPE
> ======================================
>
> Application servers using libgssrpc with RPCSEC_GSS protection may be
> vulnerable to an active network attack that fools the server into
> disabling cryptographic protection of RPC arguments and return values.
> The primary component affected by this vulnerability is kadmind, which
> serves the kadm5 and iprop RPC protocols.
>
> Using this vulnerability, an active network attacker on the path
> between a replica KDC and the primary KDC can cause kadmind to reveal
> the contents of an incremental update reply in plain text. This
> update may contain sensitive Kerberos database material. Any key
> information in the incremental update will be encrypted in the master
> key, but if the master password is not strong, a dictionary attack may
> reveal the unencrypted key data. Updating to the 1.22.3 release on
> the primary kadmin server is sufficient to prevent this attack.
>
> We believe that this vulnerability is not exploitable in the kadm5
> protocol, because the kadmin client makes an INIT remote procedure
> call before issuing any substantive RPCs. Because only the server is
> fooled into disabling encryption, the client will abort the kadmin
> session when it tries to decode the INIT reply. We also considered
> scenarios where an attacker replays a modified copy of a recorded
> kadmin session, but we believe that the replay cache and the use of
> subkeys prevent this variant of the attack.
>
> The CVE in this category is CVE-2026-118380.
>
>
> WINDOWS CLIENT VULNERABILITIES
> ==============================
>
> Applications using leashdll are vulnerable to a buffer overflow
> (possibly leading to code execution) if the KDC supplies a very long
> prompt banner. Exploitating this vulnerability may be impossible
> because only the FAST OTP preauth mechanism permits large prompt
> banners, and the leashdll APIs do not set a FAST armor cache.
>
> If an application supplies principal names from an untrusted source to
> leashdll initial ticket functions (such as Leash_kinit_dlg()), an
> attacker could cause buffer overflows by supplying long names,
> possibly leading to code execution.
>
> On a Windows host with untrusted users, an attacker could potentially
> trick kfwlogon into setting ACL rights on a file of the attacker's
> choice via a hard link.
>
> On a Windows host with untrusted users, a user could create a krb5.ini
> file in the default per-machine location prior to Kerberos for Windows
> installation. This file would then be used by other users, allowing
> code execution via module loading.
>
>
> ACKNOWLEDGEMENTS
> ================
>
> The following individuals and organizations contributed to the
> discovery of the vulnerabilities fixed in the 1.22.3 release:
>
> Arthur Chan
> Rahul Hoysala
> Alexandru-Ionut Jipa
> Cem Onat Karagun
> David Korczynski
> Erin Liman
> Tristan Madani
> Alejandro Pacheco
> Julien Rische
> Moritz Theile
> Rickey Visinski
>
> Ada Logics
> AISLE
> Anthropic
> AWS Security
> Deutsche Bank
> Red Hat
> Talence Security
>
> REVISION HISTORY
> ================
>
> 2026-11-09 original release
>
> Copyright (C) 2026 Massachusetts Institute of Technology
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