Security Bulletin: AIX is vulnerable to a denial of service due to libxml2 (CVE-2022-49043)

Vulnerability in libxml2 could allow a remote attacker to cause a denial of service (CVE-2022-49043). AIX uses libxml2 as part of its XML parsing functions.

## Vulnerability Details

**CVEID:**CVE-2022-49043
**DESCRIPTION:** xmlXIncludeAddNode in xinclude.c in libxml2 before 2.11.0 has a use-after-free.
**CWE:**CWE-416: Use After Free
**CVSS Source:** [email protected]
**CVSS Base score:** 8.1
**CVSS Vector:**(CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H)

## Affected Products and Versions

Affected Product(s)| Version(s)
—|—
AIX| 7.2
AIX| 7.3
VIOS| 3.1
VIOS| 4.1

The following fileset levels are vulnerable:

Fileset| Lower Level| Upper Level
—|—|—
bos.rte.control| 7.2.5.0| 7.2.5.204
bos.rte.control| 7.3.1.0| 7.3.1.3
bos.rte.control| 7.3.2.0| 7.3.2.2
bos.rte.control| 7.3.3.0| 7.3.3.0

To find out whether the affected filesets are installed on your systems, refer to the lslpp command found in AIX user’s guide.

Example: lslpp -L | grep -i bos.rte.control

## Remediation/Fixes

**A. APARS**

IBM has assigned the following APARs to this problem:

AIX Level| APAR| SP
—|—|—
7.2.5| IJ54061| SP10
7.3.1| IJ54257| N/A
7.3.2| IJ54258| SP04
7.3.3| IJ54059| SP01

VIOS Level| APAR| FP
—|—|—
3.1.4| IJ54061| 3.1.4.60
4.1.0| IJ54258| 4.1.0.40
4.1.1| IJ54059| 4.1.1.10

Subscribe to the APARs here:

https://www.ibm.com/support/pages/apar/[apar number]

By subscribing, you will receive periodic email alerting you to the status of the APAR, and a link to download the fix once it becomes available.

**B. FIXES**

IBM strongly recommends addressing the vulnerability now.

AIX and VIOS fixes are available. The fixes are cumulative and address previously issued AIX/VIOS libxml2 security bulletins with respect to SP and TL.

The AIX and VIOS fixes can be downloaded via https from:

https://aix.software.ibm.com/aix/efixes/security/libxml2_fix7.tar

The link above is to a tar file containing this signed advisory, fix packages, and OpenSSL signatures for each package. The fixes below include prerequisite checking. This will enforce the correct mapping between the fixes and AIX Technology Levels.

AIX Level| Interim Fix
—|—
7.2.5.7| IJ54061s9a.250409.epkg.Z
7.2.5.8| IJ54061s9a.250409.epkg.Z
7.2.5.9| IJ54061s9a.250409.epkg.Z
7.3.1.2| IJ54257s4a.250409.epkg.Z
7.3.1.3| IJ54257s4a.250409.epkg.Z
7.3.1.4| IJ54257s4a.250409.epkg.Z
7.3.2.1| IJ54258s3a.250409.epkg.Z
7.3.2.2| IJ54258s3a.250409.epkg.Z
7.3.2.3| IJ54258s3a.250409.epkg.Z
7.3.3.0| IJ54059s0a.250409.epkg.Z

Please note that the above table refers to AIX TL/SP level as opposed to fileset level, i.e., 7.3.2.3 is AIX 7300-02-03.

Please reference the Affected Products and Version section above for help with checking installed fileset levels.

VIOS Level| Interim Fix
—|—
3.1.4.31| IJ54061s9a.250409.epkg.Z
3.1.4.41| IJ54061s9a.250409.epkg.Z
3.1.4.50| IJ54061s9a.250409.epkg.Z
4.1.0.10| IJ54258s3a.250409.epkg.Z
4.1.0.21| IJ54258s3a.250409.epkg.Z
4.1.0.30| IJ54258s3a.250409.epkg.Z
4.1.1.0| IJ54059s0a.250409.epkg.Z

To extract the fixes from the tar file:

tar xvf libxml2_fix7.tar

cd libxml2_fix7

Verify you have retrieved the fixes intact:

The checksums below were generated using the “openssl dgst -sha256 [filename]” command as the following:

openssl dgst -sha256| filename
—|—
56dc4e356577beca93a26e51fb4ebc7a4999c29f364379449d34b483b109c16b| IJ54059s0a.250409.epkg.Z
235b40168e231ae14445408127f2de17bcce9acbcb089b0516b891966cf999a7| IJ54061s9a.250409.epkg.Z
54d57bc8ab645dd3aac686b732ca410bffafe7cbc867c5e7e1eb2d1ccefe80cd| IJ54257s4a.250409.epkg.Z
0aab6c40bd3d42b53c81a58039836eae1d68fbd64c06a7a25df33221647a5171| IJ54258s3a.250409.epkg.Z

These sums should match exactly. The OpenSSL signatures in the tar file and on this advisory can also be used to verify the integrity of the fixes. If the sums or signatures cannot be confirmed, contact IBM Support at http://ibm.com/support/ and describe the discrepancy.

openssl dgst -sha256 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file]

openssl dgst -sha256 -verify [pubkey_file] -signature [ifix_file].sig [ifix_file]

Published advisory OpenSSL signature file location:

https://aix.software.ibm.com/aix/efixes/security/libxml2_advisory7.asc.sig

**C. FIX AND INTERIM FIX INSTALLATION**

If possible, it is recommended that a mksysb backup of the system be created. Verify it is both bootable and readable before proceeding.

To preview a fix installation:

installp -a -d fix_name -p all # where fix_name is the name of the

# fix package being previewed.

To install a fix package:

installp -a -d fix_name -X all # where fix_name is the name of the

# fix package being installed.

Interim fixes have had limited functional and regression testing but not the full regression testing that takes place for Service Packs; however, IBM does fully support them.

Interim fix management documentation can be found at:

https://www.ibm.com/support/pages/managing-interim-fixes-aix

To preview an interim fix installation:

emgr -e ipkg_name -p # where ipkg_name is the name of the

# interim fix package being previewed.

To install an interim fix package:

emgr -e ipkg_name -X # where ipkg_name is the name of the

# interim fix package being installed.

## Workarounds and Mitigations

None

##