IBM AIX/PowerVM VIOS format string

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
7.9$5k-$25k2.34

Summaryinfo

A vulnerability, which was classified as very critical, was found in IBM AIX and PowerVM VIOS. The affected element is an unknown function. The manipulation results in format string. This vulnerability is known as CVE-2026-16821. Attacking locally is a requirement. No exploit is available.

Detailsinfo

A vulnerability, which was classified as very critical, was found in IBM AIX and PowerVM VIOS (affected version not known). Affected is some unknown functionality. The manipulation with an unknown input leads to a format string vulnerability. CWE is classifying the issue as CWE-134. The product uses a function that accepts a format string as an argument, but the format string originates from an external source. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 could allow a local attacker to gain elevated privileges due to a format string vulnerability.

The advisory is available at ibm.com. This vulnerability is traded as CVE-2026-16821 since 07/24/2026. The exploitability is told to be easy. Local access is required to approach this attack. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 08/29/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

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Vendor

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License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.9
VulDB Meta Temp Score: 7.9

VulDB Base Score: 8.8
VulDB Temp Score: 8.8
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.0
CNA Vector (ibm): 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Format string
CWE: CWE-134 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

07/24/2026 CVE reserved
08/28/2026 +35 days VulDB entry created
08/29/2026 +0 days Advisory disclosed
08/29/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: ibm.com

Advisory: ibm.com
Status: Confirmed

CVE: CVE-2026-16821 (🔒)
GCVE (CVE): GCVE-0-2026-16821
GCVE (VulDB): GCVE-100-396930

Entryinfo

Created: 08/29/2026 00:18
Changes: 08/29/2026 00:18 (61)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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