User guide

Important Notes
40
Release Notes for Cisco 2500 Series for Cisco IOS Release 12.0 T
78-5563-07 Rev.H0
Listing all possible addresses—especially all possible broadcast addresses—to which attack packets
may be sent is complicated. If you do not need to forward any legitimate syslog traffic received on an
interface, you can block all syslog traffic arriving on that interface. Remember that blocking will affect
traffic routed through the Cisco IOS device as well as traffic destined to the device; if the IOS device is
expected to forward syslog packets, you will have to do the detailed filtering. Because input access lists
impact system performance, install them with caution—especially on systems running very near their
capacity.
Software Versions and Fixes
Many Cisco software images have been or will be specially reissued to correct this vulnerability. For
example, regular released Cisco IOS version 12.0(2) is vulnerable, as are interim versions 12.0(2.1)
through 12.0(2.3). The first fixed interim version of Release12.0 mainline software is Release12.0(2.4).
However, a special release, 12.0(2a), contains only the fix for this vulnerability and does not include
any other bug fixes from later 12.0 interim releases.
If you are running Release 12.0(2) and want to fix this problem without risking possible instability
presented by installing the 12.0(2.4) interim release, you can upgrade to Release 12.0(2a). Release
12.0(2a) is a “code branch” from the Release 12.0(2) base, which will merge back into the Release 12.0
mainline at Release 12.0(2.4).
Special releases, like 12.0(2a), are one-time, spot fixes, and they will not be maintained. Thus, the
upgrade path from Release 12.0(2a) is to Release 12.0(3).
Table 7 specifies information about affected and repaired software versions.
Note All dates within this table are subject to change.
Table 7 Affected and Repaired Software Versions
Cisco IOS Major Release Description Special Fix
1
First Fixed
Interim Release
2
Fixed Maintenance
Release
3
Unaffected Releases
11.2 and earlier
releases—all variants
Unaffected early releases
(no syslog server)
Unaffected Unaffected Unaffected
11.3, 11.3 T, 11.3 DA,
11.3 MA, 11.3 NA,
11.3 WA, 11.3(2)XA
11.3 releases without syslog
servers
Unaffected Unaffected Unaffected
Releases Based on 11.3
11.3 AA 11.3 early deployment for
AS58xx
11.3(7)AA2,
8-JAN-1999
4
11.3(7.2)AA 11.3(8)AA, 15-FEB-1999
11.3 DB 11.3 for Cisco NRP routing
blade in Cisco 6400 xDSL
DSLAM
11.3(7)DB2,
18-JAN-1999
Releases Based on 12.0
12.0 12.0 Mainline 12.0(2a),
8-JAN-1999
12.0(2.4) 12.0(3), 1-FEB-1999
12.0 T 12.0 new technology early
deployment
12.0(2a)T1,
11-JAN-1999
12.0(2.4)T 12.0(3)T, 15-FEB-1999