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Security Bulletin: IBM i is affected by BIND being too lenient accepting records with forged data and consuming excessive CPU when a resolver is performing DNSSEC validation [CVE-2025-40778, CVE-2026-1519].

Security Bulletin


Summary

Domain Name System for IBM i is vulnerable to BIND being too lenient when accepting records from answers allowing an attack to inject forged data into cache [CVE-2025-40778], and consuming excessive CPU when a resolver is performing DNSSEC validation and encounters a maliciously crafted zone [CVE-2026-1519] as described in the vulnerability details section.

Vulnerability Details

CVEID:   CVE-2025-40778
DESCRIPTION:   Under certain circumstances, BIND is too lenient when accepting records from answers, allowing an attacker to inject forged data into the cache. This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.39-S1, and 9.20.9-S1 through 9.20.13-S1.
CWE:   CWE-349: Acceptance of Extraneous Untrusted Data With Trusted Data
CVSS Source:   security-officer@isc.org
CVSS Base score:   8.6
CVSS Vector:   (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N)

CVEID:   CVE-2026-1519
DESCRIPTION:   If a BIND resolver is performing DNSSEC validation and encounters a maliciously crafted zone, the resolver may consume excessive CPU. Authoritative-only servers are generally unaffected, although there are circumstances where authoritative servers may make recursive queries (see: https://kb.isc.org/docs/why-does-my-authoritative-server-make-recursive…). This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.46, 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.46-S1, and 9.20.9-S1 through 9.20.20-S1.
CWE:   CWE-606: Unchecked Input for Loop Condition
CVSS Source:   security-officer@isc.org
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 Product(s)Version(s)
IBM i7.6
IBM i7.5
IBM i7.4
IBM i7.3

Remediation/Fixes

 

IBM i Release5770-SS1 Option 31 
PTF Number(s)
PTF Download Link(s)
7.6SJ09207https://www.ibm.com/mysupport/s/fix-information?legacy=SJ09207
7.5SJ09205https://www.ibm.com/mysupport/s/fix-information?legacy=SJ09205
7.4SJ09206https://www.ibm.com/mysupport/s/fix-information?legacy=SJ09206
7.3SJ09213https://www.ibm.com/mysupport/s/fix-information?legacy=SJ09213

IBM recommends that all users running unsupported versions of affected products upgrade to a supported version of the affected product.

Workarounds and Mitigations

None

Get Notified about Future Security Bulletins

References

Off

Acknowledgement

Change History

01 May 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:
01 May 2026

Initial Publish date:
01 May 2026

UID

ibm17271474