What is the CVSS score of EUVD-2026-62423?

EUVD-2026-62423 has a CVSS 3.1 base score of 8.2 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L. EPSS exploitation probability: 0.6%.

Which versions of IBM AIX are affected by EUVD-2026-62423?

IBM AIX 7.2/7.3 and PowerVM VIOS 4.1 contain an unauthenticated remote file overwrite vulnerability in the nimesis registration service that allows attackers with network access to overwrite critical…. A patch is available.

How to fix or mitigate EUVD-2026-62423?

Within 24 hours, audit network firewall rules to identify and restrict all inbound access to the nimesis registration service to trusted administrative systems only, and create an inventory of all AIX 7.2, 7.3, and PowerVM VIOS 4.1 systems in your environment. Within 7 days, obtain and apply the vendor-released patches to all identified IBM AIX 7.2 and 7.3 instances and PowerVM VIOS 4.1 deployments, prioritizing production systems and those directly accessible from external networks. Within 30 days, complete validation that all patches have been deployed enterprise-wide, implement network segmentation to further restrict nimesis service access to authorized hosts only, and conduct a post-patch audit to confirm the vulnerable registration service is no longer accepting unauthenticated path traversal inputs.

IBM AIX EUVD-2026-62423

| CVE-2026-15061 HIGH

Path Traversal (CWE-22)

2026-08-19 ibm

GHSA-hvmr-4fv5-38xw

Path Traversal IBM Aix Powervm Vios

8.2

CVSS 3.1 · Vendor: ibm

Severity by source

Vendor (ibm) PRIMARY

8.2 HIGH

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

vuln.today AI

8.2 HIGH

Network-exposed registration service with no auth (PR:N, AV:N); path traversal write is straightforward (AC:L); no confidentiality loss, but arbitrary file overwrite yields High integrity and Low availability impact.

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

4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (ibm).

CVSS VectorVendor: ibm

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

Low

Lifecycle Timeline

Analysis Generated

Aug 19, 2026 - 15:10 vuln.today

CVE Published

Aug 19, 2026 - 14:33 cve.org

HIGH 8.2

DescriptionCVE.org

IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 's nimesis registration service could allow a remote attacker to overwrite files due to path traversal.

AnalysisAI

Unauthenticated remote file overwrite in IBM AIX 7.2/7.3 and PowerVM VIOS 4.1 is possible via the nimesis registration service, which fails to sanitize path traversal sequences in client-supplied input. An attacker with network access to the nimesis service can write arbitrary content to locations outside the intended directory, potentially overwriting sensitive system files such as cron jobs, init scripts, or authentication databases. No public exploit or active exploitation has been identified at time of analysis, though the CVSS vector (AV:N/AC:L/PR:N/UI:N) indicates this is straightforwardly exploitable without authentication.

Technical ContextAI

The nimesis service is a component of IBM AIX's NIM (Network Installation Management) subsystem, which facilitates network-based provisioning and client registration across IBM Power environments. The CWE-22 (Path Traversal) root cause indicates that the service accepts file path arguments from remote clients and writes to those paths without adequately normalizing or restricting traversal sequences such as '../'. CPE data (cpe:2.3:a:ibm:aix:*:*:*:*:*:*:*:* and cpe:2.3:a:ibm:powervm_vios:*:*:*:*:*:*:*:*) confirms the flaw spans the full version ranges of IBM AIX and PowerVM VIOS 4.1, as enumerated by NVD. The CVSS impact subscore reflects no confidentiality loss but High integrity impact, consistent with an arbitrary-write primitive where content and path are attacker-controlled.

RemediationAI

IBM has released a patch, available through the vendor advisory at https://www.ibm.com/support/pages/node/7283858. Administrators should apply the fix immediately following IBM's guidance; an exact patched version number was not specified in the data available at time of analysis and must be confirmed from the advisory. As a compensating control prior to patching, restrict network access to the nimesis registration service using host-based firewall rules (e.g., AIX IPFilter or iptables on VIOS) to allow only trusted NIM master hosts to reach the nimesis port - this eliminates remote unauthenticated reach while preserving legitimate NIM functionality. If NIM client registration is not actively in use, consider disabling the nimesis service via SRC (System Resource Controller) with 'stopsrc -s nimesis'; note this will disrupt NIM-based provisioning workflows.