CVE-2026-64208: crypto/krb5, rxrpc: Fix lack of pre-decrypt/pre-verify length checks

Greg Kroah-Hartman <[email protected]>
Newsgroups org.kernel.vger.linux-cve-announce
Message-ID <2026072411-CVE-2026-64208-5d8d@gregkh>
From: Greg Kroah-Hartman <[email protected]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

crypto/krb5, rxrpc: Fix lack of pre-decrypt/pre-verify length checks

Change the krb5 crypto library to provide facilities to precheck the length
of the message about to be decrypted or verified.

Fix AF_RXRPC to make use of this to validate DATA packets secured with
RxGK.

The Linux kernel CVE team has assigned CVE-2026-64208 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.16 with commit 9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a and fixed in 6.18.34 with commit 585f9f6aef5c4542ac9d6ec45cd7dbc7df9af3ff
	Issue introduced in 6.16 with commit 9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a and fixed in 7.0.11 with commit 9217017f4bce53dddb8d547837f1f707045d64ad
	Issue introduced in 6.16 with commit 9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a and fixed in 7.1 with commit 2b50aceafe6606ea52ed42aadd1b4d44a188aade

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-64208
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	Documentation/crypto/krb5.rst
	crypto/krb5/krb5_api.c
	include/crypto/krb5.h
	include/trace/events/rxrpc.h
	net/rxrpc/rxgk.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/585f9f6aef5c4542ac9d6ec45cd7dbc7df9af3ff
	https://git.kernel.org/stable/c/9217017f4bce53dddb8d547837f1f707045d64ad
	https://git.kernel.org/stable/c/2b50aceafe6606ea52ed42aadd1b4d44a188aade
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