CVE-2026-16931Network attack vector

Unauthenticated service interruption via zero-length TCP options

Published Aug 12, 2026 · Updated Aug 12, 2026

Infinite-loop denial of service in IBM operating system releases 7.3 through 7.6 allows remote attackers to interrupt service. The vendor discloses TCP option handling as the locus but not the affected routine or precise parsing operation that leaves the loop unable to exit. Network reachability is sufficient; authentication and user interaction are not required, and the documented consequence is limited to system availability.

CVSS severity7.5
High
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite-loop denial of service in IBM operating system releases 7.3 through 7.6 allows remote attackers to interrupt service. The vendor discloses TCP option handling as the locus but not the affected routine or precise parsing operation that leaves the loop unable to exit. Network reachability is sufficient; authentication and user interaction are not required, and the documented consequence is limited to system availability.

The record

CVE
CVE-2026-16931
Published
Aug 12, 2026
Updated
Aug 12, 2026
Vendor
IBM
Product
IBM i
Classifications
CWE-835, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 12, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=7.3
  2. Affected versionversion=7.4
  3. Affected versionversion=7.5
  4. Affected versionversion=7.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

IBM · IBM iversion=7.3; version=7.4; version=7.5; version=7.6

Published CVSS scores

7.5IBMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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