CVE-2026-89106

Executive Summary

CVE-2026-89106 is an insufficient input validation vulnerability in SAP UI5 (CWE-183, "Permissive List of Allowed Inputs") that manifests under certain unspecified configurations. An attacker holding only low privileges can submit specially crafted content that is subsequently rendered in a victim user's browser, resulting in low-severity impacts to confidentiality and integrity with no availability impact. The affected product is confirmed as SAP UI5, but no specific affected version range has been published, and no vendor patch, workaround, or public proof-of-concept currently exists.

Technical Analysis

The root cause is classified as CWE-183, a permissive list of allowed inputs. This means the component accepts input that should have been rejected or sanitized rather than validating against a sufficiently restrictive allow-list. Per the NVD description, the weakness is conditional: SAP UI5 "does not perform sufficient input validation under certain configurations." This wording implies the defect is configuration-dependent rather than universally present. Certain deployments or runtime configuration states cause user-supplied content to bypass whatever validation is otherwise in place.

The attack surface is the rendering path in which attacker-supplied content is later displayed in a victim's browser. The critical timing element is that submission and rendering are distinct events: the attacker submits crafted content at one point, and a different user (the victim) renders it later. This is characteristic of stored or reflected content rendering in web front ends built on the SAP UI5 framework. Because the flaw is an input-validation weakness of the CWE-183 class, the mechanism should be understood at that class level: inadequate enforcement of an allow-list permits content that the framework should not have accepted.

The CVSS vector CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N describes the following conditions precisely:

• AV:N (Network) — exploitable remotely over a network.
• AC:H (High) — attack complexity is high; success depends on conditions outside the attacker's direct control, consistent with the "certain configurations" requirement.
• PR:L (Low) — the attacker requires only low privileges.
• UI:R (User Interaction Required) — a victim must interact, consistent with the rendering-in-browser requirement.
• S:C (Scope Changed) — the impact escapes the vulnerable component's security authority; the victim's browser context is a different security scope from the validating component.
• C:L / I:L — only low confidentiality and integrity impact.
• A:N — no availability impact.

No specific functions, endpoints, parameters, or file paths are disclosed in the NVD description or the CNA title, which is empty. Consequently, no code-level detail can be stated beyond the vulnerability class. There is no CVE-2026-89106 entry in CISA KEV, no public exploit code, and no Nuclei template. Specific implementation details are therefore unavailable and are not extrapolated here.

Exploitation Scenarios

No public proof-of-concept or exploit code exists for CVE-2026-89106. The attack chain below is inferred at the vulnerability-class level from the description and CVSS vector; no specific implementation artifacts are asserted.

1. Reconnaissance / target identification. The attacker identifies a network-reachable application rendered with SAP UI5. Because the vulnerability is configuration-dependent, the attacker probes configurations under which input validation is insufficient. The attacker needs only low privileges (PR:L), meaning any authenticated low-privilege account — or another low-privilege access path — is sufficient to attempt submission.

2. Triggering the flaw class. The attacker submits specially crafted content through a normal, permitted input channel. Unlike a privileged exploit, this step leverages ordinary low-privilege submission rights. The supplied content contains input that the allow-list should have rejected but, under the affected configuration, does not. Nothing in the available data specifies the exact input format, parameter, or injection string.

3. Payload delivery / execution method. The distinguishing property is deferred rendering: the crafted content is stored or otherwise retained, then rendered in a victim's browser when that victim interacts with the affected UI (UI:R). The scope change (S:C) indicates the effect is felt in the victim's browser security context rather than the server-side component that performed (insufficient) validation. At the vulnerability-class level, a permissive input allow-list allows content to reach the browser that validation was intended to neutralize.

4. Post-exploitation impact. Impact is limited to low confidentiality and integrity loss (C:L, I:L) with no availability impact (A:N). The consequences are confined to manipulation or limited disclosure within the victim's rendered session, not broad system compromise. The scope-change element means the effect lands outside the validating component's authority.

Impact Assessment

Business impact is limited but non-zero. The CVSS base score is 4.4 (Medium), derived from remote network exploitability gated by high complexity, low privileges, and required victim interaction. The Scope:Changed classification is the most significant qualitative factor: effects cross from the vulnerable validating component into the victim browser's security context, which is why scope change elevates the vector despite low C/I subscores. Confidentiality and integrity impacts are low, so the realistic worst case is limited data exposure and content manipulation within a rendered user session rather than data destruction or service disruption. Affected systems are SAP UI5 deployments where the insufficient-validation configuration exists. Blast radius is bounded by (a) the configuration dependency — only deployments in the affected configuration are exposed, and (b) the required victim interaction, which means exploitation cannot be fully automated against a passive victim. No EPSS score has been published by FIRST.org at the time of writing, and CVE-2026-89106 is not listed in CISA KEV, so there is no confirmed evidence of active exploitation in the wild.

Detection Guidance

Sigma Rule

title: SAP UI5 Insufficient Input Validation - Suspicious Content Submission (CVE-2026-89106)
id: 8f3c1a2e-4b6d-4e7a-9c1f-2d5e7a9b0c11
status: experimental
description: Detects submission of crafted content to SAP UI5 applications that may exploit insufficient input validation (CWE-183). Tune to local request patterns.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-89106
author: valtersit.com
date: 2026/01/01
tags:
  - attack.t1190
logsource:
  category: webserver
detection:
  selection_method:
    cs-method:
      - POST
      - PUT
  selection_target:
    cs-uri-query|contains:
      - 'sap-ui'
      - 'sap.ui'
    cs-uri-stem|contains:
      - '.html'
      - '.jsp'
  selection_payload:
    cs-uri-query|contains:
      - '<script'
      - '%3Cscript'
      - 'onerror='
      - 'onload='
      - 'javascript:'
  condition: selection_method and selection_target and selection_payload
falsepositives:
  - Legitimate application content that includes scripting syntax
level: medium

YARA Rule

rule CVE_2026_89106_SAP_UI5_Input_Validation
{
    meta:
        description = "Detects crafted payloads targeting SAP UI5 insufficient input validation (CWE-183, CVE-2026-89106)"
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-89106"
        date = "2026-01-01"
        severity = "medium"

    strings:
        $ui5a = "sap-ui-core" ascii nocase
        $ui5b = "sap.ui" ascii nocase
        $ui5c = "sap-ui-bootstrap" ascii nocase
        $p1 = "<script" ascii nocase
        $p2 = "onerror=" ascii nocase
        $p3 = "onload=" ascii nocase
        $p4 = "javascript:" ascii nocase
        $p5 = "document.cookie" ascii nocase

    condition:
        any of ($ui5*) and 1 of ($p*)
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-89106 SAP UI5 Insufficient Input Validation - Possible Crafted Content Submission"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"sap-ui"; nocase; http.request_body; content:"<script"; nocase; http.request_body; content:"onerror="; nocase; classtype:web-application-attack; reference:cve,2026-89106; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-89106; sid:202689106; rev:1;)

alert http any any -> any any (msg:"CVE-2026-89106 SAP UI5 Insufficient Input Validation - Script Payload in UI Request"; flow:established,to_server; http.method; content:"PUT"; http.uri; content:"sap.ui"; nocase; http.request_body; content:"javascript:"; nocase; classtype:web-application-attack; reference:cve,2026-89106; sid:202689107; rev:1;)

Elastic Detection

sequence by source.ip with maxspan=5m
  [ network where network.protocol == "http" and http.request.method in ("POST", "PUT") and
      wildcard(http.request.uri, "*sap-ui*") ]
  [ network where network.protocol == "http" and
      ( wildcard(http.request.body, "*<script*") or
        wildcard(http.request.body, "*onerror=*") or
        wildcard(http.request.body, "*onload=*") or
        wildcard(http.request.body, "*javascript:*") ) ]

Splunk SPL Query

index=web sourcetype=access_combined
(method=POST OR method=PUT)
(uri_path="*sap-ui*" OR uri="*sap.ui*" OR uri_path="*.html")
| eval suspicious=if(match(uri_query, "(?i)(<script|%3Cscript|onerror=|onload=|javascript:)") OR match(form_data, "(?i)(<script|onerror=|onload=|javascript:)"), 1, 0)
| where suspicious=1
| stats count min(_time) as first_seen max(_time) as last_seen values(clientip) as src_ips values(uri) as requested_uris by host
| where count > 0
| sort - count

Wazuh OSSEC Rule

<group name="web,sap,cve-2026-89106,">
  <rule id="2026891" level="8">
    <decoded_as>web-accesslog</decoded_as>
    <field name="method">POST|PUT</field>
    <field name="url">sap-ui|sap.ui</field>
    <match>script|onerror|onload|javascript:</match>
    <description>CVE-2026-89106: Possible SAP UI5 crafted content submission targeting insufficient input validation (CWE-183).</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>web_application_attack,pci_dss_6.5.1,</group>
  </rule>

  <rule id="2026892" level="3">
    <if_sid>2026891</if_sid>
    <description>CVE-2026-89106: SAP UI5 input validation weakness observed (recon or low-confidence event).</description>
    <group>web_scan,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence is 0/4. There is no patch evidence from any tracked source, no vendor fix, no workaround, and no published affected-version range. The following guidance is therefore structural and must be validated against a vendor advisory when one becomes available.

1. Immediate mitigations:

   • Apply defense-in-depth input validation on any content path that stores user-supplied values for later rendering, enforcing a strict allow-list rather than a permissive one (directly addressing CWE-183).
   • Deploy output encoding at the point of rendering, independent of upstream validation, so that crafted content cannot execute in the victim browser context.
   • Review SAP UI5 configuration states to identify and disable any configuration under which validation is insufficient, since exploitability is conditional on configuration.
   • Enforce least privilege so that low-privilege accounts cannot reach the affected submission paths unnecessarily.
   • Deploy the detection rules above to identify crafted-content submission attempts while a fix is pending.

2. Patch/upgrade steps:

   • No patch reference exists at this time. Monitor the vendor's security notes and the NVD entry for CVE-2026-89106.
   • Subscribe to SAP security note releases and apply SAP UI5 security fixes as soon as an official note covering this CVE is published.
   • Re-assess the CVSS vector and affected-version data once the vendor publishes authoritative details.

3. Long-term hardening:

   • Adopt a strict allow-list validation standard for all web front-end input that feeds rendered output.
   • Implement a Content Security Policy to reduce the impact of unescaped or unvalidated content reaching the browser.
   • Add framework-level regression testing for validation bypass under all supported configuration modes.
   • Track configuration baselines for SAP UI5 deployments and audit deviations regularly.

References

• NVD — CVE-2026-89106: https://nvd.nist.gov/vuln/detail/CVE-2026-89106
• CWE-183 — Permissive List of Allowed Inputs: https://cwe.mitre.org/data/definitions/183.html
• MITRE ATT&CK T1190 — Exploit Public-Facing Application: https://attack.mitre.org/techniques/T1190/
• FIRST.org EPSS: no score published for this CVE at the time of writing
• CISA Known Exploited Vulnerabilities Catalog: CVE-2026-89106 is not listed (no exploit-in-the-wild evidence at time of writing)

No threat actor campaigns or in-the-wild exploitation have been associated with CVE-2026-89106 in the available data.