VulnerabilityPublished 13 Aug 2026

CVE-2026-16896: IBM · Time-of-check Time-of-use (TOCTOU) Race Condition

Affects IBMSource CVE Database V5

Not known to be exploited · CVSS 7.1 High.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

7.1High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 0% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
IBM	Affected 7.3 – 7.6 4 affected builds	Fixed in–

CPE configurations (8)

cpe:2.3:a:ibm:i:7.6:*:*:*:*:*:*:*
cpe:2.3:a:ibm:i:7.6.0:*:*:*:*:*:*:*
cpe:2.3:a:ibm:i:7.5:*:*:*:*:*:*:*
cpe:2.3:a:ibm:i:7.5.0:*:*:*:*:*:*:*
cpe:2.3:a:ibm:i:7.4:*:*:*:*:*:*:*
cpe:2.3:a:ibm:i:7.4.0:*:*:*:*:*:*:*

AI-suggested

Until an official fix is available, restrict local access to trusted users only and monitor for suspicious activity related to file access. Follow IBM's official communications for updates on patches or mitigations.

Description

CVE-2026-16896 is a high-severity vulnerability in IBM i versions 7.3, 7.4, 7.5, and 7.6. It involves a time-of-check to time-of-use (TOCTOU) race condition that could allow a local authenticated attacker to gain unauthorized access to files. The vulnerability does not have a confirmed patch or remediation level as of the published date. No known exploits are reported in the wild.

Impact

Successful exploitation could allow a local authenticated attacker to access files they are not authorized to, potentially leading to unauthorized disclosure and modification of sensitive information. There is no indication of impact on system availability. The vulnerability requires local access and some privileges, limiting remote exploitation possibilities.

Summary

This vulnerability (CVE-2026-16896) affects IBM i operating system versions 7.3 through 7.6. It is classified as a CWE-367 TOCTOU race condition, where a local authenticated attacker might exploit the timing gap between checking a resource and using it to access files without proper authorization. The CVSS 3.1 base score is 7.1, indicating high severity, with attack vector local, low attack complexity, low privileges required, no user interaction, unchanged scope, and high impact on confidentiality and integrity but no impact on availability.

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.
Implementation
The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.
Implementation
When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.
Architecture and Design
Limit the interleaving of operations on files from multiple processes.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V1.11.3 (opens in a new tab)
V11.1.6 (opens in a new tab)
V1.11.2 (opens in a new tab)
Attack patterns
Leveraging Race Conditions via Symbolic Links (opens in a new tab)
Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

ibm.com/support/pages/node/7283293 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

CPE configurations (8)

Description

AI analysisMachine-generated, updated 21 Aug 2026, 13:29 UTC

WeaknessesCWE-367

Technical details

References

Community reviews

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