CVE-2026-90921

Executive Summary

CVE-2026-90921 is a denial-of-service vulnerability in IBM Maximo AI Service versions 9.1.0 and 9.2.0, caused by improper handling of malformed frames that results in termination of the host process. An unauthenticated remote attacker can exploit this over the network without user interaction, yielding a full availability impact. No public proof-of-concept, Nuclei template, or exploit code currently exists, and no vendor patch has been identified.

Technical Analysis

The vulnerability is classified under CWE-130 (Improper Handling of Length Parameter Inconsistency), which describes a class of defects where a parser fails to correctly reconcile a declared length value against the actual size or structure of the data it receives. In this instance, the affected IBM Maximo AI Service improperly handles malformed frames. The NVD description does not disclose the specific protocol, parser component, function name, or framing format involved, so the following analysis is limited to the vulnerability class.

Frames in network and inter-process communication typically carry length fields, headers, or delimiters that a receiving parser uses to determine message boundaries. When a frame's declared length is inconsistent with the actual payload — for example, a length field that exceeds or truncates the delivered data — a robust parser must reject or safely bound the input. If it does not, the inconsistency can drive the process into an unhandled exception, an out-of-bounds access in the parsing logic, or an unbounded allocation. In CVE-2026-90921 the observed outcome is termination of the host process, i.e., a crash-based denial of service rather than memory corruption with a demonstrated code-execution path.

The attack surface is the network-exposed frame processing endpoint of the AI Service. Per the CVSS vector, the attack is network-reachable (AV:N), requires no privileges (PR:N), no user interaction (UI:N), and is low complexity (AC:L). The scope is unchanged (S:U), meaning the impact is confined to the vulnerable component's security authority. Confidentiality and integrity are unaffected (C:N/I:N); only availability is high (A:H). This profile is consistent with a remotely triggerable crash of the service host process. Because the service is a Maximo AI component, an availability loss may also degrade dependent asset-management functionality that relies on AI features. No further code-level detail is available from the provided data and none is inferred here.

Exploitation Scenarios

No public PoC or exploit code exists for CVE-2026-90921. The attack chain below is inferred strictly from the vulnerability class (CWE-130 malformed frame handling) and the NVD description stating that malformed frames cause host process termination.

1. Reconnaissance / target identification: An attacker identifies internet- or network-exposed IBM Maximo AI Service instances running versions 9.1.0 or 9.2.0, for example via Shodan or product fingerprinting of Maximo web components. Exposed management or AI-service ports become candidate targets.

2. Triggering the flaw class: The attacker delivers crafted frames to the service's frame-processing interface whose length parameters or framing structure are inconsistent — carrying malformed or mismatched length fields. Per CWE-130, the parser fails to handle this inconsistency correctly.

3. Payload / execution method: At the vulnerability-class level, the malformed frame is sent as raw network traffic; no authentication or user interaction is required (PR:N/UI:N). The exact wire format is not disclosed in the available data, so no specific frame bytes, endpoints, or parameters can be reliably specified.

4. Post-exploitation impact: Successful delivery causes the host process to terminate, producing a denial of service. Given AC:L, repeated delivery can sustain the outage. There is no indicated lateral movement, data theft, or code execution tied to this CVE, as C/I are unaffected.

Impact Assessment

The primary impact is availability loss. With A:H, a successful attack renders the IBM Maximo AI Service unavailable by terminating its host process. Because the vulnerability is unauthenticated and remotely reachable (AV:N, PR:N, UI:N, AC:L), the barrier to exploitation is low and the attack can be repeated trivially, extending the outage. The unchanged scope (S:U) limits impact to the vulnerable component, but organizations using Maximo AI Service for operational AI-driven asset workflows may experience secondary disruption if those workflows depend on the crashed service. Blast radius is determined by how many Maximo AI Service instances are exposed and how many business processes depend on them. Confidentiality and integrity exposure are nil per the vector. CVSS base score is 7.5 (High).

Detection Guidance

Sigma Rule

title: IBM Maximo AI Service Host Process Crash - Malformed Frame DoS (CVE-2026-90921)
id: 6b1f2a90-2c4d-4e11-9a77-0d5f1c90921a
status: experimental
description: Detects termination of the Maximo AI Service host process potentially caused by malformed frame handling.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-90921
author: valtersit.com
logsource:
  category: process_termination
  product: windows
detection:
  selection_proc:
    Image|endswith:
      - '\maximo_ai_service.exe'
      - '\java.exe'
    CommandLine|contains: 'Maximo'
  selection_crash:
    EventID:
      - 1000
      - 1001
  condition: selection_proc and selection_crash
falsepositives:
  - Legitimate service restarts or maintenance
  - OOM conditions unrelated to malformed frames
level: high
tags:
  - attack.t1499
  - cve.2026.90921

YARA Rule

rule CVE_2026_90921_Maximo_Malformed_Frame
{
    meta:
        description = "Detection aid for CVE-2026-90921 malformed frame handling in IBM Maximo AI Service"
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-90921"
        date = "2026-01-01"
    strings:
        $s1 = "Maximo AI Service" ascii wide nocase
        $s2 = "maximo" ascii wide nocase
        $len1 = "Content-Length" ascii nocase
        $len2 = "frame_length" ascii nocase
    condition:
        (uint16(0) == 0x5A4D or uint32(0) == 0x464C457F) and
        any of ($s*) and any of ($len*)
}

Suricata IDS Rule

alert tcp any any -> any any (msg:"CVE-2026-90921 IBM Maximo AI Service malformed frame DoS attempt"; flow:established,to_server; content:"Maximo"; http_header; content:"Content-Length"; http_header; pcre:"/Content-Length:\s*[0-9]{6,}/Hi"; threshold: type both, track by_src, count 20, seconds 10; classtype:attempted-dos; reference:cve,2026-90921; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-90921; sid:9092101; rev:1;)

Elastic Detection

process where event.type == "end" and
  process.name in ("maximo_ai_service.exe", "java.exe") and
  process.command_line : "*Maximo*" and
  process.exit_code != 0

Splunk SPL Query

index=main (sourcetype=maximo:* OR sourcetype=syslog)
| search ("Maximo AI Service" OR maximo_ai_service)
| search (terminated OR crash OR "process exited" OR SIGSEGV OR SIGABRT)
| stats count min(_time) as first_seen max(_time) as last_seen by host, process
| where count > 0

Wazuh OSSEC Rule

<group name="ibm_maximo,cve-2026-90921,">
  <rule id="909210" level="12">
    <decoded_as>json</decoded_as>
    <field name="app">MaximoAIService</field>
    <match>terminated|crash|SIGSEGV|SIGABRT|malformed frame</match>
    <description>CVE-2026-90921: IBM Maximo AI Service host process terminated - possible malformed frame DoS</description>
    <mitre>
      <id>T1499</id>
    </mitre>
    <group>dos,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source).

1. Immediate mitigations: Isolate IBM Maximo AI Service instances from untrusted networks; restrict access to the frame-processing interface using network ACLs, segmentation, or a reverse proxy that rejects malformed frames. Rate-limit inbound connections to reduce the ability to sustain a crash-based outage. Where possible, configure the host process to auto-restart under a supervisor to shorten downtime windows. (The NVD data lists no vendor-provided workarounds.)

2. Patch/upgrade steps: No patch is currently available. Monitor IBM's official security advisories and the NVD entry for updated fix information, and track the exact affected versions (9.1.0, 9.2.0). Do not apply unverified patches.

3. Long-term hardening: Enforce strict input validation and safe frame-length handling in any custom integrations; deploy signature-based network monitoring for malformed-frame traffic (see Detection Guidance); maintain network segmentation for AI service components; and institute continuous CVE monitoring for Maximo components. Note the absence of CISA KEV listing, PoC, exploit code, and the unavailability of an EPSS score indicates no observed active exploitation as of the data provided.

References

• NVD — CVE-2026-90921: https://nvd.nist.gov/vuln/detail/CVE-2026-90921
• CWE-130 — Improper Handling of Length Parameter Inconsistency: https://cwe.mitre.org/data/definitions/130.html
• MITRE ATT&CK T1499 — Endpoint Denial of Service: https://attack.mitre.org/techniques/T1499/
• IBM Security Bulletins: https://www.ibm.com/support/pages/security-bulletins
• FIRST EPSS: no score available for this CVE at time of writing.

No threat actor campaigns or exploit-in-the-wild evidence are associated with CVE-2026-90921 in the provided data; the CVE is not listed in CISA KEV.