CVE-2026-16896

Local file access via TOCTOU race

Published Aug 13, 2026 · Updated Aug 13, 2026

TOCTOU race in Network Authentication Service in IBM operating system releases 7.3 through 7.6 allows local users unauthorized file access. The service checks a file and later uses the checked object, while IBM has not disclosed the precise operations or the method for changing the target between those operations. Low-privileged local access is required; successful exploitation exposes file contents and permits file modification without interrupting service.

CVSS severity7.1
High
EPSS probability0.07%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

TOCTOU race in Network Authentication Service in IBM operating system releases 7.3 through 7.6 allows local users unauthorized file access. The service checks a file and later uses the checked object, while IBM has not disclosed the precise operations or the method for changing the target between those operations. Low-privileged local access is required; successful exploitation exposes file contents and permits file modification without interrupting service.

The record

CVE
CVE-2026-16896
Published
Aug 13, 2026
Updated
Aug 13, 2026
Vendor
IBM
Product
IBM i
Classifications
CWE-367, T1005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 13, 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 vectorlocal
Required privilegesauthenticated

What is affected?

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

Published CVSS scores

7.1IBMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
T1005Data from Local System

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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