CVE-2026-76976

Executive Summary

CVE-2026-76976 is a cross-site scripting (XSS) vulnerability (CWE-79) in SAP NetWeaver Application Server ABAP, specifically affecting applications rendered through SAP GUI for HTML. The flaw occurs because user-supplied content in certain functionality is not sufficiently sanitized, allowing an authenticated attacker to inject malicious content that executes in another user's browser when that victim interacts with the affected content. The impact is scoped (S:C) but limited to low confidentiality and integrity impact with no availability impact, yielding a CVSS 3.1 base score of 5.4 (Medium). Because exploitation requires authentication (PR:L) and user interaction (UI:R), the vulnerability is most relevant to insider, lateral-movement, and post-authentication abuse scenarios rather than unauthenticated internet mass-exploitation.

Technical Analysis

CVE-2026-76976 is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The affected component is SAP NetWeaver Application Server ABAP as exposed through SAP GUI for HTML (WebGUI). SAP GUI for HTML translates classic SAP GUI Dynpro screens into an HTML-based interface served to a browser, meaning any user-controllable field that is later re-rendered into an HTML document represents a potential injection sink.

Per the NVD description, the root cause is insufficient sanitization of user-supplied content "in certain functionality" within applications based on SAP GUI for HTML. The vulnerability is a stored or reflected XSS pattern — the description states an authenticated attacker can "send malicious content to another user," and if the victim interacts with the affected content, "malicious scripts could be executed in the victim's browser context." This victim-to-victim delivery model (attacker → stored/delivered content → victim browser) is the classic signature of stored/persistent XSS, where the injected payload is persisted server-side or delivered through a message/notification-style flow and later rendered to a different user without adequate output encoding.

Key technical facts derivable from the data:

• Attack vector: Network (AV:N) — the payload is delivered over HTTP/HTTPS to the victim's browser through the ABAP web tier.
• Privileges required: Low (PR:L) — the attacker must possess a valid authenticated session in the SAP system.
• User interaction: Required (UI:R) — the victim must interact with (render/open/view) the affected content for script execution to occur.
• Scope: Changed (S:C) — successful exploitation allows the injected script to affect resources beyond the security scope of the vulnerable component (i.e., the victim's browser security context).
• Impact: Low on confidentiality (C:L) and integrity (I:L); none on availability (A:N).

The CWE-79 classification and the "insufficient sanitization" language confirm an output-encoding/input-validation defect. The precise ABAP classes, function modules, ICF services, or parameter names involved are not disclosed in the supplied NVD text, and no CNA title, affected version list, OSV package mapping, or patch reference was provided. No code-level or endpoint-level detail is available, and none is asserted here.

A note on severity: CVSS 5.4 reflects the requirement for authentication and victim interaction. Under the changed-scope model, however, the practical severity can exceed the base score when the victim holds elevated SAP authorizations — XSS in a privileged user's session can be leveraged to perform actions with that user's authority, making role distribution a primary risk amplifier.

Exploitation Scenarios

No public PoC, Nuclei template, or exploit code is available for CVE-2026-76976; the attack chain below is inferred at the vulnerability-class level from the NVD description. No specific function names, endpoints, or parameters are fabricated.

1) Reconnaissance / target identification. The attacker requires authenticated access to the SAP NetWeaver ABAP system (PR:L) and identifies a functionality in the SAP GUI for HTML interface that accepts user-supplied content and later renders that content to another user. Candidate surfaces are any screens or flows where one user's input becomes visible to a second user in the WebGUI. Publicly reachable SAP NetWeaver ABAP web entry points can be enumerated by defenders and attackers alike via fingerprinting of the SAP WebGUI title and HTML markers (see Shodan dorks above).

2) Triggering the flaw class. The attacker submits content containing script markup into the identified user-supplied field. Because the application "does not sufficiently sanitize" that content, the malicious markup is retained and re-emitted into a page delivered to a different user. This is a stored/persistent XSS precondition: the untrusted input is not neutralized on input or on output.

3) Payload / execution. When the victim interacts with the affected content — opening or viewing the page/notification containing the injected markup — the browser parses the unsanitized response and executes the embedded script within the victim's browser context and the origin of the SAP web application. Execution is gated on victim interaction (UI:R), which is why the exploit is not a fire-and-forget unauthenticated attack.

4) Post-exploitation impact. Because the scope is changed (S:C), the script executes with the victim's session authority in the SAP application origin. Realistic consequences of scripts running in a SAP WebGUI session include acting on the authenticated SAP session on the victim's behalf (integrity impact, I:L) and reading content available to that session (confidentiality impact, C:L). The NVD description explicitly bounds this to low C/I impact and no availability impact. There is no evidence in the supplied data of remote code execution, authentication bypass, or privilege escalation beyond the victim's own session.

Threat-actor relevance: no exploit-in-the-wild evidence, no CISA KEV listing, and no named campaign are associated with this CVE in the provided data. The realistic adversary profile is an authenticated insider or a low-privileged account holder targeting higher-privileged SAP users (e.g., administrators, approvers) whose sessions carry elevated authority.

Impact Assessment

• Confidentiality (Low, C:L): Script execution in the victim's browser context can expose data visible to the victim's session. Impact is constrained and scoped to what the victim can already access.
• Integrity (Low, I:L): The attacker can cause the victim's session to perform limited actions under the victim's identity. No evidence of server-side/backend integrity destruction.
• Availability (None, A:N): No denial-of-service component is described.
• Scope (Changed, S:C): Security authority shifts from the vulnerable web component to the victim's browser context — this is the defining reason base severity is 5.4 and not lower.

Blast radius is a function of deployment and user role, not of the CVE score alone:

• Affected systems: SAP NetWeaver Application Server ABAP deployments that expose SAP GUI for HTML. Because no affected-version list is available, treat all such deployments as potentially affected until SAP confirms otherwise.
• Privileged-session leverage: The most severe real-world outcome occurs when the victim is a high-privileged user; XSS in an admin session can be chained to sensitive in-application actions using that session's authorization. This raises effective business risk above the headline 5.4.
• No mass-exploitation profile: PR:L and UI:R make this a targeted, authenticated, social/interaction-dependent attack. Large-scale unauthenticated exploitation across the internet is not supported by the CVSS profile.
• Lateral and social engineering risk: The victim-to-victim delivery model can be used internally to pivot trust — e.g., an attacker impersonates a trusted internal workflow notification to induce the victim to interact.

Business impact includes potential unauthorized disclosure of SAP business data within the victim's authorization, and unauthorized transactional actions under the victim's identity; regulatory exposure follows from the sensitivity of data the victim can access.

Detection Guidance

Detection strategy: identify script-bearing payloads crossing the SAP WebGUI web tier, and alert on anomalous content in user-supplied fields that is later rendered to other users. Because no patch, PoC, or endpoint detail is public, detections below target the CWE-79 class generically and should be tuned to the specific SAP functionality once disclosed.

Sigma Rule

title: Potential XSS Payload in SAP NetWeaver ABAP WebGUI Requests
id: 3f1c9b6e-7a2d-4f8b-9c4e-76976aa10001
status: experimental
description: Detects common XSS payload markers in HTTP requests and responses to SAP GUI for HTML (WebGUI), indicating attempts to exploit insufficient sanitization (CWE-79) per CVE-2026-76976.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-76976
author: valtersit.com
date: 2026/01/01
logsource:
  category: webserver
  product: sap
detection:
  selection_uri:
    cs-uri-stem|contains:
      - '/sap/bc/gui/sap/its/webgui'
      - '/sap/bc/gui/sap/its/'
  selection_payload:
    cs-uri-query|contains:
      - '<script'
      - 'javascript:'
      - 'onerror='
      - 'onload='
      - 'document.cookie'
      - '%3Cscript'
      - 'alert('
  condition: selection_uri and selection_payload
fields:
  - c-ip
  - cs-username
  - cs-uri-stem
  - cs-uri-query
falsepositives:
  - Legitimate application fields containing HTML-escaped code samples
  - Security scanner traffic
level: medium
tags:
  - attack.t1059.007
  - cve.2026.76976

YARA Rule

rule CVE_2026_76976_SAP_WebGUI_XSS_Payload
{
    meta:
        description = "Detects script-injection payload patterns associated with CWE-79 in SAP GUI for HTML / NetWeaver ABAP responses and logs (CVE-2026-76976)."
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-76976"
        date = "2026-01-01"
        severity = "medium"

    strings:
        $webgui1 = "/sap/bc/gui/sap/its/webgui" ascii nocase
        $webgui2 = "/sap/bc/gui/sap/its/" ascii nocase

        $xss1 = "<script" ascii nocase
        $xss2 = "</script>" ascii nocase
        $xss3 = "javascript:" ascii nocase
        $xss4 = "onerror=" ascii nocase
        $xss5 = "onload=" ascii nocase
        $xss6 = "document.cookie" ascii nocase
        $xss7 = "String.fromCharCode" ascii nocase

    condition:
        any of ($webgui*) and 1 of ($xss*)
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-76976 SAP NetWeaver ABAP WebGUI Potential XSS Payload"; flow:established,to_server; http.uri; content:"/sap/bc/gui/sap/its/"; nocase; http.uri; content:"script"; nocase; http.header; content:"User-Agent"; nocase; reference:cve,2026-76976; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-76976; classtype:web-application-attack; metadata:affected_product SAP_NetWeaver_ABAP; sid:7697601; rev:1;)

alert http any any -> any any (msg:"CVE-2026-76976 SAP WebGUI XSS Marker in Request Body or URI"; flow:established,to_server; content:"<script"; nocase; http.uri; content:"/sap/bc/gui/sap/its/"; nocase; reference:cve,2026-76976; classtype:web-application-attack; sid:7697602; rev:1;)

Elastic Detection

sequence by source.ip with maxspan=5m
  [ network where
      url.path : "/sap/bc/gui/sap/its/*" and
      url.query : ("*<script*", "*javascript:*", "*onerror=*", "*onload=*") ]

Splunk SPL Query

index=web OR index=proxy sourcetype=access_combined OR sourcetype=sap_webgui
| eval uri = coalesce(uri, url, cs_uri_stem)
| eval query = coalesce(uri_query, cs_uri_query)
| where like(uri, "%/sap/bc/gui/sap/its/%")
| where (like(lower(query), "%script%") OR like(lower(query), "%onerror=%") OR like(lower(query), "%onload=%") OR like(lower(query), "%javascript:%") OR like(lower(query), "%document.cookie%"))
| stats count min(_time) as first_seen max(_time) as last_seen values(query) as payloads by src_ip, uri, user
| where count > 0
| sort - count

Wazuh OSSEC Rule

<group name="sap,web,attack,">
  <rule id="769760" level="10">
    <decoded_as>web-accesslog</decoded_as>
    <match>/sap/bc/gui/sap/its/</match>
    <description>CVE-2026-76976: Request to SAP GUI for HTML (WebGUI) endpoint</description>
  </rule>

  <rule id="769761" level="12">
    <if_sid>769760</if_sid>
    <regex><script|javascript:|onerror=|onload=|document\.cookie</regex>
    <description>CVE-2026-76976: Possible XSS payload sent to SAP WebGUI (CWE-79)</description>
    <mitre>
      <id>T1059.007</id>
    </mitre>
    <group>cve_2026_76976,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source). No vendor fix, workaround, or SAP Security Note is identified in the available data. Organizations must treat this as an open vulnerability and compensate with controls until SAP publishes guidance.

1) Immediate mitigations

• Restrict and monitor who can reach the SAP GUI for HTML interface; enforce strong authentication and least-privilege authorization so few accounts have the reach needed to inject content.
• Require MFA and short session timeouts for privileged SAP users to reduce the window in which an XSS-compromised session can be abused.
• Deploy a Web Application Firewall (WAF) in front of the SAP web tier with XSS filtering/response inspection, treating it as a stopgap, not a fix.
• Enforce a strict Content-Security-Policy (CSP) on the WebGUI to reduce inline script execution risk, where the application can tolerate it.
• Increase logging/alerting on the WebGUI and review user-supplied fields that are later rendered to other users.
• Apply normal browser and endpoint protections; educate high-privilege users about interacting with unexpected in-application content.

2) Patch / upgrade steps

• Monitor the SAP Support Portal for a Security Note addressing this issue (assigned CVE-2026-76976) and for the affected NetWeaver Application Server ABAP component and version range.
• Once a note is released, identify exposed SAP GUI for HTML deployments via the note's component/version matrix, schedule patching in the standard SAP change cycle, and prioritize systems with high-privilege user populations.
• After patching, re-validate output encoding on the affected functionality as part of regression testing.

3) Long-term hardening

• Enforce contextual output encoding and input validation for all user-supplied content in SAP web-facing functionality.
• Maintain an asset inventory of SAP NetWeaver ABAP systems and WebGUI exposure; continuously track SAP Security Notes and subscribe to SAP security advisories.
• Adopt least privilege and role separation across SAP accounts to limit the authority reachable from any single compromised session.
• Integrate SAP security monitoring into the SOC (web logs forwarded to SIEM, rules above) and run regular authenticated web application assessments.

References

1. NVD — CVE-2026-76976: https://nvd.nist.gov/vuln/detail/CVE-2026-76976
2. MITRE CWE-79 — Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'): https://cwe.mitre.org/data/definitions/79.html
3. SAP Security Notes / SAP Support Portal (vendor advisories — note for CVE-2026-76976 not yet identified): https://support.sap.com/en/my-support/knowledge-base/security-notes-news.html
4. MITRE ATT&CK — T1059.007 Command and Scripting Interpreter: JavaScript: https://attack.mitre.org/techniques/T1059/007/
5. FIRST EPSS (no score available at time of writing): https://www.first.org/epss/

Exploit-in-the-wild status: no public PoC, no Nuclei template, no exploit code, no CISA KEV entry, and no named threat-actor campaign are associated with CVE-2026-76976 in the data provided. Affected version ranges and vendor patch details remain undisclosed; treat all SAP NetWeaver ABAP deployments exposing SAP GUI for HTML as potentially affected pending vendor confirmation.