CVE-2026-16946

Privilege escalation via strncat off-by-one overflow

Published Aug 20, 2026 · Updated Aug 20, 2026

Heap buffer overflow in IBM AIX 7.2, 7.3, and IBM PowerVM VIOS 4.1 allows local users to gain elevated privileges via local execution. IBM's IJ57009 APAR states that on Power10 and later systems the vector-instruction strncat path writes the terminating null byte at destination address plus one, creating a one-byte heap overflow in bos.mp64. Reachability requires local code execution on affected AIX or VIOS hosts, and the retrieved public records do not describe a remote trigger or user-interaction requirement.

CVSS severity7.8
High
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in IBM AIX 7.2, 7.3, and IBM PowerVM VIOS 4.1 allows local users to gain elevated privileges via local execution. IBM's IJ57009 APAR states that on Power10 and later systems the vector-instruction strncat path writes the terminating null byte at destination address plus one, creating a one-byte heap overflow in bos.mp64. Reachability requires local code execution on affected AIX or VIOS hosts, and the retrieved public records do not describe a remote trigger or user-interaction requirement.

The record

CVE
CVE-2026-16946
Published
Aug 20, 2026
Updated
Aug 20, 2026
Vendor
OpenBMC Project
Product
AIX
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 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=7.2
  2. Affected versionversion=7.3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

OpenBMC Project · AIXversion=7.2; version=7.3
OpenBMC Project · PowerVM Virtual I/O Serverversion=4.1

Published CVSS scores

7.8NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.8NVDAV:L/AC:L/Au:S/C:C/I:C/A:C

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

T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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