Security Bulletin
Summary
IBM i is vulnerable to multiple vulnerabilities [CVE-2026-16858, CVE-2026-16867, CVE-2026-16868, CVE-2026-16853, CVE-2026-17226, CVE-2026-16859, CVE-2026-16878, CVE-2026-16861, CVE-2026-17212, CVE-2026-18020, CVE-2026-17649, CVE-2026-16871, CVE-2026-18671, CVE-2026-18680, CVE-2026-17502] in NetServer as described in the vulnerability details section.
Vulnerability Details
CVEID: CVE-2026-16859
DESCRIPTION: IBM i could allow a remote attacker to obtain sensitive information due to an out-of-bounds read.
CWE: CWE-125: Out-of-bounds Read
CVSS Source: IBM
CVSS Base score: 5.3
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)
CVEID: CVE-2026-17226
DESCRIPTION: IBM i could allow a remote authenticated attacker to obtain sensitive information or cause a denial of service due to an out-of-bounds read.
CWE: CWE-125: Out-of-bounds Read
CVSS Source: IBM
CVSS Base score: 5.4
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L)
CVEID: CVE-2026-16853
DESCRIPTION: IBM i could allow a remote attacker to obtain sensitive information due to an out-of-bounds read.
CWE: CWE-125: Out-of-bounds Read
CVSS Source: IBM
CVSS Base score: 6.5
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L)
CVEID: CVE-2026-16868
DESCRIPTION: IBM i could allow a remote attacker to cause a denial of service due to the use of uninitialized memory during ASN.1 length processing.
CWE: CWE-908: Use of Uninitialized Resource
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-2026-16867
DESCRIPTION: IBM i could allow a remote attacker to access server resources with the privileges of an authenticated user due to improper authentication during NTLM session negotiation.
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)
CVEID: CVE-2026-16858
DESCRIPTION: IBM i could allow a remote attacker to cause a denial of service due to an out-of-bounds write.
CWE: CWE-787: Out-of-bounds Write
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-2026-17502
DESCRIPTION: IBM i could allow a remote attacker to cause a denial of service due to an out-of-bounds write.
CWE: CWE-787: Out-of-bounds Write
CVSS Source: IBM
CVSS Base score: 8.6
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H)
CVEID: CVE-2026-16871
DESCRIPTION: IBM i could allow a remote authenticated attacker to obtain sensitive information due to a heap buffer overflow.
CWE: CWE-787: Out-of-bounds Write
CVSS Source: IBM
CVSS Base score: 4.3
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N)
CVEID: CVE-2026-18671
DESCRIPTION: IBM i could allow an authenticated attacker to force a NetServer server thread exception, caused by an integer overflow during bounds checking in request processing. The attacker could exploit this vulnerability to cause a temporary denial of service.
CWE: CWE-190: Integer Overflow or Wraparound
CVSS Source: IBM
CVSS Base score: 6.5
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L)
CVEID: CVE-2026-18680
DESCRIPTION: IBM i could allow an authenticated attacker to trigger stack corruption within the NetServer server job, caused by incomplete bounds checking. The attacker could exploit this vulnerability to cause a system level denial of service.
CWE: CWE-787: Out-of-bounds Write
CVSS Source: IBM
CVSS Base score: 6.5
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
CVEID: CVE-2026-17649
DESCRIPTION: IBM i could allow a remote attacker to obtain sensitive information due to an out-of-bounds read.
CWE: CWE-125: Out-of-bounds Read
CVSS Source: IBM
CVSS Base score: 5.3
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)
CVEID: CVE-2026-18020
DESCRIPTION: IBM i could allow a remote attacker to cause a denial of service due to an off-by-one error in bounds checking.
CWE: CWE-125: Out-of-bounds Read
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-2026-17212
DESCRIPTION: IBM i could allow a remote attacker to cause a denial of service due to an out-of-bounds read.
CWE: CWE-125: Out-of-bounds Read
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-2026-16861
DESCRIPTION: IBM i could allow a remote attacker to cause a denial of service due to an out-of-bounds read.
CWE: CWE-125: Out-of-bounds Read
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-2026-16878
DESCRIPTION: IBM i could allow a remote authenticated attacker to obtain sensitive information due to an out-of-bounds read.
CWE: CWE-125: Out-of-bounds Read
CVSS Source: IBM
CVSS Base score: 5.4
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L)
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.
| IBM i Release | 5770-999 PTF Number(s) | PTF Download Link(s) |
| 7.6 | MJ10939 | https://www.ibm.com/mysupport/s/fix-information?legacy=MJ10939 |
| 7.5 | MJ10938 | https://www.ibm.com/mysupport/s/fix-information?legacy=MJ10938 |
| 7.4 | MJ10937 | https://www.ibm.com/mysupport/s/fix-information?legacy=MJ10937 |
| 7.3 | MJ10936 | https://www.ibm.com/mysupport/s/fix-information?legacy=MJ10936 |
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
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:
12 August 2026
Initial Publish date:
12 August 2026
UID
ibm17283573