SAP patches critical Python SDK flaw that could expose OAuth credentials

Issue affects multi-tenant applications running on SAP Business Technology Platform

SAP has patched a maximum-severity flaw in its Cloud SDK for Python that could expose OAuth credentials in multi-tenant BTP applications, alongside 19 other vulnerabilities in its October security updates.

The vulnerability, tracked as CVE-2026-89111 , carries a Common Vulnerability Scoring System (CVSS) score of 10.0 out of 10, the highest possible rating.

In a security advisory published on 13 October, SAP said the flaw could enable an attacker to redirect an application's OAuth2 client credentials to a server under their control.

The issue affects multi-tenant applications running on SAP Business Technology Platform (BTP) that use the company's official Python software development kit (SDK) to access BTP services.

SAP's October security updates address 20 vulnerabilities across multiple products, including two other critical flaws affecting its enterprise software.

How the vulnerability could expose credentials

The Cloud SDK for Python handles authentication for SAP services using an application's client ID and client secret.

The credentials are used to obtain access tokens through the OAuth2 authentication mechanism.

According to the vulnerability details, an attacker who can control the tenant subdomain supplied by an application to the SDK could potentially manipulate where authentication requests are sent.

This could cause the application to transmit its OAuth2 client credentials to an attacker-controlled server, potentially allowing the credentials to be stolen.

The attack does not require the attacker to have existing privileges, although control over the relevant tenant subdomain is a necessary condition.

SAP addressed the vulnerability by introducing a validation check that rejects tenant subdomains that do not conform to the expected format.

The fix was included in version 0.45.2 , released on 21 August 2026. However, subsequent development introduced inconsistencies in how the validation was applied.

Versions 0.53.0 to 0.55.0, released between 10 and 18 September, did not consistently enforce the check when applications used the SDK's Destination service module.

The problem arose after version 0.53.0 moved the module to shared code for requesting authentication tokens, which did not include the required validation. SAP restored the check in version 0.55.1, released on 18 September. Its release notes state that tenant subdomains containing URL delimiters now trigger an immediate error rather than allowing credentials to be routed to an attacker-controlled endpoint.

Organisations using the Cloud SDK for Python should review their installed versions and consult SAP's latest security guidance to determine whether they need to update their software.

Two other critical flaws fixed

SAP's October updates also address two other critical vulnerabilities affecting its enterprise software products.

CVE-2026-89110 affects SAP NetWeaver Visual Composer. The broken access control vulnerability could allow a remote attacker with limited privileges to gain complete control of vulnerable systems.

Another flaw, indexed as CVE-2026-89108, affects SAP Manufacturing Integration and Intelligence. It could allow attackers who already have administrator privileges to gain control over the underlying system by creating an account with elevated privileges on the Java application.

The latest disclosures follow several other serious SAP security issues addressed in recent months.

In August, SAP patched CVE-2026-58231 in its Commerce Cloud e-commerce platform. Threat intelligence firm Defused subsequently reported that the vulnerability was being actively exploited.

In September, the company also fixed CVE-2026-44756, a memory corruption vulnerability in SAP Kernel code that security researchers at Onapsis dubbed OVERPASS.

Last year, SAP patched CVE-2025-42944 , a maximum-severity vulnerability with a CVSS score of 10.0 affecting the Remote Method Invocation service in SAP NetWeaver.

The flaw could allow unauthorised attackers to execute system commands remotely.