Security Bulletin
Summary
IBM i is vulnerable to multiple vulnerabilities [CVE-2026-17223, CVE-2026-17206, CVE-2026-17208, CVE-2026-16929, CVE-2026-17004, CVE-2026-18846, CVE-2026-17197, CVE-2026-17217, CVE-2026-17199, CVE-2026-17229, CVE-2026-16982] in host servers, and a buffer overflow [CVE-2026-17220] in host, debug, telnet, and Distributed Relational Database Architecture (DRDA) / Distributed Data Management and (DDM) servers as described in the vulnerability details section.
Vulnerability Details
CVEID: CVE-2026-18846
DESCRIPTION: IBM i is vulnerable to a buffer overflow from improperly validating client data. By sending malformed requests to one of the host servers, a remote attacker could leverage this vulnerability to cause a denial-of-server (DoS) for that server.
CWE: CWE-787: Out-of-bounds Write
CVSS Source: IBM
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)
CVEID: CVE-2026-17223
DESCRIPTION: IBM i could allow a remote authenticated attacker to execute arbitrary code due to a buffer overflow.
CWE: CWE-787: Out-of-bounds Write
CVSS Source: IBM
CVSS Base score: 8.8
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
CVEID: CVE-2026-17206
DESCRIPTION: IBM i could allow a remote attacker to execute arbitrary code due to a buffer overflow.
CWE: CWE-787: Out-of-bounds Write
CVSS Source: IBM
CVSS Base score: 8.1
CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H)
CVEID: CVE-2026-17208
DESCRIPTION: IBM i could allow a remote attacker to cause a denial of service due to a buffer overflow.
CWE: CWE-122: Heap-based Buffer Overflow
CVSS Source: IBM
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)
CVEID: CVE-2026-16929
DESCRIPTION: IBM i could allow a remote authenticated attacker to obtain sensitive information due to a buffer overflow.
CWE: CWE-787: Out-of-bounds Write
CVSS Source: IBM
CVSS Base score: 5.3
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
CVEID: CVE-2026-17004
DESCRIPTION: IBM i could allow a remote attacker to cause a denial of service due to an infinite loop.
CWE: CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')
CVSS Source: IBM
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)
CVEID: CVE-2026-17217
DESCRIPTION: IBM i could allow a remote attacker to cause a denial of service due to a buffer overflow.
CWE: CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CVSS Source: IBM
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)
CVEID: CVE-2026-17199
DESCRIPTION: IBM i could allow a remote attacker to cause a denial of service due to unbounded resource allocation.
CWE: CWE-770: Allocation of Resources Without Limits or Throttling
CVSS Source: IBM
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)
CVEID: CVE-2026-17229
DESCRIPTION: IBM i could allow a remote attacker to cause a denial of service due to an infinite loop.
CWE: CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')
CVSS Source: IBM
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)
CVEID: CVE-2026-16982
DESCRIPTION: IBM i could allow a remote attacker to cause a denial of service due to a heap buffer overflow.
CWE: CWE-787: Out-of-bounds Write
CVSS Source: IBM
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)
CVEID: CVE-2026-17220
DESCRIPTION: IBM i could allow a remote attacker to cause a denial of service and modify authentication metadata due to a buffer overflow.
CWE: CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CVSS Source: IBM
CVSS Base score: 8.2
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H)
CVEID: CVE-2026-17197
DESCRIPTION: IBM i could allow a remote attacker to bypass security restrictions due to improper validation of client-asserted identity.
CWE: CWE-287: Improper Authentication
CVSS Source: IBM
CVSS Base score: 8.1
CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H)
Affected Products and Versions
| Affected Product(s) | Version(s) |
| IBM i | 7.6 |
| IBM i | 7.5 |
| IBM i | 7.4 |
| IBM i | 7.3 |
Remediation/Fixes
IBM strongly recommends addressing the vulnerability now.
Host Servers
-- UPDATED 08/13/2026 --
Due to the stricter security requirements from the Host Servers PTFs, the QFileSvr.400 file system may not connect under certain circumstances. The following PTFs address the issue.
QFileSvr.400
| IBM i Release | 5770-SS1 PTF Number(s) | PTF Download Link(s) |
| 7.6 | SJ11191 | https://www.ibm.com/mysupport/s/fix-information?legacy=SJ11191 |
| 7.5 | SJ11190 | https://www.ibm.com/mysupport/s/fix-information?legacy=SJ11190 |
| 7.4 | SJ11189 | https://www.ibm.com/mysupport/s/fix-information?legacy=SJ11189 |
| 7.3 | SJ11188 | https://www.ibm.com/mysupport/s/fix-information?legacy=SJ11188 |
-- END UPDATED --
Debug Server
| IBM i Release | 5770-SS1 PTF Number(s) | PTF Download Link(s) |
| 7.6 | SJ10899 | https://www.ibm.com/mysupport/s/fix-information?legacy=SJ10899 |
Telnet
| IBM i Release | 5770-SS1 PTF Number(s) | PTF Download Link(s) |
| 7.6 | SJ11022 | https://www.ibm.com/mysupport/s/fix-information?legacy=SJ11022 |
DRDA/DDM
| IBM i Release | 5770-SS1 PTF Number(s) | PTF Download Link(s) |
| 7.6 | SJ10848 | https://www.ibm.com/mysupport/s/fix-information?legacy=SJ10848 |
IBM recommends users running unsupported versions of affected products upgrade to a supported and fixed version of affected products.
Workarounds and Mitigations
None
Get Notified about Future Security Bulletins
References
Acknowledgement
Change History
13 Aug 2026: QFileSvr.400 PTFs added
12 Aug 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:
13 August 2026
Initial Publish date:
12 August 2026
UID
ibm17283578