[krbdev.mit.edu #8959] git commit

[Greg Hudson via RT]

<URL: https://krbdev.mit.edu/rt/Ticket/Display.html?id=8959 >


Add recursion limit for ASN.1 indefinite lengths

The libkrb5 ASN.1 decoder supports BER indefinite lengths.  It
computes the tag length using recursion; the lack of a recursion limit
allows an attacker to overrun the stack and cause the process to
crash.  Reported by Demi Obenour.

CVE-2020-28196:

In MIT krb5 releases 1.11 and later, an unauthenticated attacker can
cause a denial of service for any client or server to which it can
send an ASN.1-encoded Kerberos message of sufficient length.

(cherry picked from commit 57415dda6cf04e73ffc3723be518eddfae599bfd)

https://github.com/krb5/krb5/commit/9239fa1d0124bdf3c78c20eb70873e3af2baabb1
Author: Greg Hudson <ghudson at mit.edu>
Commit: 9239fa1d0124bdf3c78c20eb70873e3af2baabb1
Branch: krb5-1.17
 src/lib/krb5/asn.1/asn1_encode.c |   16 +++++++++-------
 1 files changed, 9 insertions(+), 7 deletions(-)