"The SAP Cloud SDK for Python contains an OAuth2 SSRF vulnerability affecting multi-tenant BTP applications. An attacker who controls the tenant_subdomain parameter can redirect OAuth2 token requests to an attacker-controlled server, causing client credentials to be exfiltrated," according to a Tuesday advisory from SAP.
CVE-2026-89111: an OAuth2 SSRF that can steal credentials
In its October 2026 security updates, SAP patched a maximum-severity vulnerability in the Cloud SDK for Python, tracked as CVE-2026-89111. The SDK is the official toolkit for developing AI agents and Python applications on SAP's Business Technology Platform (BTP) services. SAP's advisory says the flaw is an OAuth2 server-side request forgery (SSRF) in multi-tenant BTP applications: an attacker who controls the tenant_subdomain parameter can redirect OAuth2 token requests to an attacker-controlled server and thereby exfiltrate client credentials. The advisory also notes the vulnerability can be exploited remotely by attackers without privileges.
October 2026 patch set: NetWeaver, Manufacturing, and a 20-flaw sweep
SAP issued fixes for 20 security flaws across multiple products in its October 2026 updates. Among the other critical issues patched, CVE-2026-89110 is a broken access control vulnerability in SAP NetWeaver Visual Composer that could let remote attackers with limited privileges fully compromise vulnerable systems. CVE-2026-89108, in SAP Manufacturing Integration and Intelligence, is a critical flaw that allows threat actors with administrator privileges to gain admin control over the underlying system by provisioning an elevated-privilege account on the underlying Java application.
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Fix the backlogShort-term mitigation: tenant_subdomain allowlisting
For customers unable to deploy the October patches immediately, SAP recommends a temporary mitigation: validate tenant_subdomain values against a known allowlist of registered tenant subdomains before passing them to SDK calls. SAP's advisory explicitly states, "Consumer applications can mitigate the vulnerability by validating tenant_subdomain against a known allowlist of registered tenant subdomains before passing it to any SDK call."
Context: recent high-severity fixes and CISA activity
The October fixes follow a string of high-severity SAP patches in recent months. In August, SAP fixed CVE-2026-58231 in its Commerce Cloud e-commerce platform; threat intelligence firm Defused flagged that flaw as being actively exploited days after SAP issued the patch. In September, SAP addressed CVE-2026-44756, a memory corruption flaw in the SAP Kernel that Onapsis researchers dubbed OVERPASS; at the time, Onapsis estimated that over 10,000 Internet-facing SAP systems used the vulnerable component and could be exposed to exploits targeting CVE-2026-44756.
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added 14 SAP security flaws to its catalog of actively exploited vulnerabilities since November 2021, and the source notes three of those were abused in ransomware attacks. Those data points underscore the operational reality SAP customers face when high-severity flaws are disclosed in widely used enterprise components.
What this means for security teams, CISA, and affected enterprises
- Security teams and technologists: The immediate operational task is straightforward in the advisory — deploy October patches for affected SAP components or implement the tenant_subdomain allowlist as a temporary control. Teams that rely on the SAP Cloud SDK for Python should prioritize validation of tenant_subdomain values in consumer applications to prevent OAuth2 token redirection and credential exfiltration.
- CISA and regulators: With 14 SAP flaws already cataloged by CISA as actively exploited since November 2021, the agency’s prior tracking of SAP vulnerabilities places October’s maximum-severity OAuth2 SSRF squarely within an established pattern that regulators and incident responders monitor for rapid exploitation.
- Affected enterprises and procurement leaders: SAP serves 99 of the 100 largest companies worldwide and reported revenues exceeding €36 billion in fiscal year 2025. That scale means a maximum-severity OAuth2 SSRF in a core SDK used to build BTP applications can have broad operational impact — enterprises must weigh immediate patching, temporary mitigations, and verification that consumer applications validate tenant_subdomain values.
SAP has provided both fixes and a clear temporary mitigation for CVE-2026-89111; the practical question that remains is whether customers will apply October's patches quickly enough to avoid follow-on exploitation, given past incidents where high-severity SAP flaws were actively abused soon after disclosure. The advisory leaves administrators with a concrete near-term choice: deploy the patch or enforce an allowlist on tenant_subdomain values to block token redirection and credential theft.
Original reporting: https://www.bleepingcomputer.com/news/security/sap-warns-of-maximum-severity-oauth2-ssrf-security-flaw/
