CVE-2026-76977: SAP UI5 CSRF Vulnerability

CVE-2026-76977 Overview

CVE-2026-76977 is a client-side security flaw in SAP UI5 caused by insufficient validation of the parent frame's origin against the configured allowlist. An unauthenticated attacker can host a malicious page that bypasses the framing restrictions enforced by SAP UI5. When an authenticated victim visits the attacker page and interacts with it, the attacker can trick the user into performing unintended actions in the embedded application. The result is a low impact on integrity, with no impact on confidentiality or availability. The weakness is classified under [CWE-1289: Improper Validation of Unsafe Equivalence in Input].

Critical Impact
An attacker-controlled page can frame SAP UI5 content and induce an authenticated user to perform unintended actions, producing a limited integrity impact.

Affected Products

SAP UI5 (versions listed in SAP Note #3783189)
SAP applications embedding vulnerable SAP UI5 framing controls
Deployments that rely on the SAP UI5 parent-frame allowlist for clickjacking protection

Discovery Timeline

2026-09-08 - CVE-2026-76977 published to the National Vulnerability Database (NVD)
2026-09-08 - Last updated in NVD database
SAP Security Patch Day - SAP released the corresponding fix documented in SAP Note #3783189

Technical Details for CVE-2026-76977

Vulnerability Analysis

SAP UI5 applications can be configured with an allowlist that restricts which parent frames may embed UI5 content. This defense is intended to prevent clickjacking and unauthorized framing. The vulnerability exists because the origin of the parent frame is not sufficiently validated against the configured allowlist. As a result, an attacker-controlled origin can satisfy the check even though it is not an intended entry.

Exploitation requires user interaction. An authenticated victim must visit the attacker's page and interact with the framed SAP UI5 content. Successful exploitation lets the attacker induce unintended state-changing actions within the SAP UI5 application in the victim's authenticated session. The technical fix and affected versions are documented in SAP Note #3783189 and the SAP Security Patch Day portal.

Root Cause

The root cause is improper validation of unsafe equivalence in input [CWE-1289]. The origin comparison logic treats non-equivalent origins as matching entries in the allowlist. This permits framing from an origin that should be rejected, defeating the intended framing restriction.

Attack Vector

The attack is delivered over the network and requires no privileges on the target SAP system. The attacker hosts a page that embeds vulnerable SAP UI5 content in a frame. When an authenticated SAP user visits the attacker page and interacts with framed UI elements, those interactions are relayed to the SAP UI5 application under the user's session. The pattern is consistent with a clickjacking style user-interface redress abuse rather than direct code execution. Refer to SAP Note #3783189 for exploitation prerequisites and technical detail.

Detection Methods for CVE-2026-76977

Indicators of Compromise

Unexpected HTTP referrers pointing to unknown external origins in SAP UI5 access logs.
Web server or CDN logs showing SAP UI5 assets being loaded within iframes from non-approved domains.
User reports of SAP interfaces appearing inside unfamiliar third-party pages.

Detection Strategies

Inspect browser and web application firewall (WAF) telemetry for framing of SAP UI5 endpoints from origins not present in the allowlist.
Correlate authenticated SAP UI5 state-changing requests with anomalous Referer or Sec-Fetch-Site: cross-site headers.
Review Content Security Policy (CSP) violation reports for frame-ancestors directive breaches on SAP UI5 hosts.

Monitoring Recommendations

Enable CSP reporting with frame-ancestors restrictions and forward reports to a centralized log store for review.
Monitor SAP audit logs for atypical user actions initiated from sessions with cross-origin request headers.
Track deployment inventory to identify SAP UI5 versions listed as vulnerable in SAP Note #3783189.

How to Mitigate CVE-2026-76977

Immediate Actions Required

Apply the SAP UI5 fix as described in SAP Note #3783189 using your standard SAP patch process.
Inventory all applications embedding SAP UI5 and confirm the parent-frame allowlist configuration is correct after patching.
Communicate to end users the risk of interacting with SAP interfaces reached through untrusted external links.

Patch Information

SAP released the corrective update on SAP Security Patch Day. The fixed versions and detailed remediation steps are published in SAP Note #3783189. Additional context is available on the SAP Security Patch Day portal. Customers should follow SAP's standard note application procedure and validate the patch in a non-production landscape prior to production rollout.

Workarounds

Enforce a strict Content-Security-Policy: frame-ancestors directive at the reverse proxy or web dispatcher to restrict framing to trusted origins.
Set the X-Frame-Options response header to SAMEORIGIN or DENY for SAP UI5 endpoints that do not require external framing.
Restrict access to SAP UI5 applications from untrusted networks until the patch is applied.

bash

# Example web dispatcher / reverse proxy headers to harden framing
Header always set Content-Security-Policy "frame-ancestors 'self' https://trusted.example.com"
Header always set X-Frame-Options "SAMEORIGIN"