Security Bulletin
Summary
Vulnerabilities in Rsyslog could cause heap buffer overflow (CVE-2026-78002). Rsyslog is used by AIX as logging daemon.
Vulnerability Details
CVEID: CVE-2026-78002
DESCRIPTION: A flaw was found in rsyslog. An unauthenticated remote attacker can trigger a heap buffer overflow in the RainerScript `replace()` function by sending specially crafted syslog messages. This vulnerability arises from an incorrect buffer size calculation during string replacement, causing memory corruption. Successful exploitation can lead to a denial of service (DoS) for the affected system.
CWE: CWE-131: Incorrect Calculation of Buffer Size
CVSS Source: secalert@redhat.com
CVSS Base score: 7.5
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Affected Products and Versions
AFFECTED PRODUCTS AND VERSIONS:
| Affected Product(s) | Version(s) |
| AIX | 7.2 |
| AIX | 7.3 |
| VIOS | 4.1 |
The vulnerabilities in the following filesets are being addressed:
key_fileset = aix
| Fileset | Lower Level | Upper Level | KEY |
| rsyslog.base | 8.22.12.0 | 8.22.12.1 | key_w_fs |
| rsyslog.base | 8.22.1273.0 | 8.22.1273.2 | key_w_fs |
Note:
A. Latest level of Rsyslog fileset is available from the web download site:
https://www.ibm.com/resources/mrs/assets?source=aixbp
To find out whether the affected filesets are installed on your systems, refer to the lslpp command found in the AIX user's guide.
Example: lslpp -L | grep -i rsyslog.base
Remediation/Fixes
A. FIXES
IBM strongly recommends addressing the vulnerability now.
The AIX and VIOS fixes can be downloaded via https from:
https://aix.software.ibm.com/aix/efixes/security/rsyslog_fix2.tar
The fileset update has a dependency on OpenSSL 3.0. OpenSSL 3.0 may be downloaded from:
https://www.ibm.com/resources/mrs/assets?source=aixbp
The link above is to a tar file containing this signed advisory, install 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.
To extract the fixes from the tar file:
tar xvf rsyslog_fix2.tar
For AIX 7.2:
tar xvf rsyslog_fix2/72rsyslog824.tar
For AIX 7.3 and VIOS 4.1:
tar xvf rsyslog_fix2/73rsyslog824.tar
IMPORTANT: 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 the fix installation:
installp -apYd . rsyslog.base
To install the fix package:
installp -aXYd .rsyslog.base
Verify you have retrieved the fixes intact:
The checksums below were generated using the following command : "openssl dgst -sha256 [file]"
| openssl dgst -sha256 | filename | KEY |
| f171baf566f3d2215a06c15e7e80f650ad875a56eaae85c7493aa937831b8895 | 72rsyslog.base | key_w_csum |
| 5f7e45935257e3cc0de827c296a1c2f2b71a5eb82f8fdb5e1180fad4170a5bca | 73rsyslog.base | key_w_csum |
The checksums below were generated using the following command : "openssl dgst -sha512 [file]"
| openssl dgst -sha512 | filename | KEY |
| 84af60235c50a52e41fd99abfb1ecc4fb0f10b6ec069bfd8442e779b11fc8d7c5f74b6380f2cbf185eecb6aba5de3be4d53f05e6352053fb01936d5f63ffd300 | 72rsyslog.base | key_4K_w_csum |
| b59b10ab355220c819476d3699de96715c8f61d26f6411c7bfb3d184ba759525969272bacc67991139029f79a611f0d33b619bacd00b88b3ba4b698acb068a51 | 73rsyslog.base | key_4K_w_csum |
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/rsyslog_fix2.asc.sig
B. 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
Get Notified about Future Security Bulletins
References
Acknowledgement
Change History
09 Oct 2026: Initial Publication
*The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin.
Disclaimer
According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES ""AS IS"" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY. In addition to other efforts to address potential vulnerabilities, IBM periodically updates the record of components contained in our product offerings. As part of that effort, if IBM identifies previously unidentified packages in a product/service inventory, we address relevant vulnerabilities regardless of CVE date. Inclusion of an older CVEID does not demonstrate that the referenced product has been used by IBM since that date, nor that IBM was aware of a vulnerability as of that date. We are making clients aware of relevant vulnerabilities as we become aware of them. "Affected Products and Versions" referenced in IBM Security Bulletins are intended to be only products and versions that are supported by IBM and have not passed their end-of-support or warranty date. Thus, failure to reference unsupported or extended-support products and versions in this Security Bulletin does not constitute a determination by IBM that they are unaffected by the vulnerability. Reference to one or more unsupported versions in this Security Bulletin shall not create an obligation for IBM to provide fixes for any unsupported or extended-support products or versions.
Document Location
Worldwide
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Document Information
Modified date:
09 October 2026
Initial Publish date:
09 October 2026
UID
ibm17291353