A critical vulnerability in SAP Cloud SDK for Python could allow attackers to steal application credentials, potentially exposing connected enterprise cloud services. The flaw affects certain multitenant applications running on SAP Business Technology Platform (BTP).
SAP disclosed the vulnerability, tracked as CVE-2026-89111, on October 13, 2026, assigning it a maximum CVSS score of 10.0. The server-side request forgery (SSRF) flaw could redirect OAuth2 authentication requests to attacker-controlled servers, exposing application credentials.
Although SAP identifies version 0.45.2 as the fix, independent testing found missing validation in certain authentication paths across six later releases. Organizations that have already updated their applications may need additional fixes.
How the SAP Cloud SDK flaw exposes credentials
The vulnerability, classified as CWE-918, involves insufficient validation of the tenant_subdomain parameter used to construct OAuth2 authentication URLs.
According to SAP's security advisory, attackers who control this parameter could redirect requests containing an application's client ID and secret to a malicious server. Stolen credentials could provide access to connected services, depending on the application's permissions.
Other cloud identity weaknesses include OAuth client ID spoofing used for account enumeration and OAuth token exposure through browser extensions. These involve different attack methods and are not connected to the SAP vulnerability.
Exploitation requires an attacker to influence the tenant-subdomain value passed to a vulnerable SDK function. No confirmed exploitation of CVE-2026-89111 had been identified in reviewed public reporting as of October 14, 2026.
The flaw was the highest-scoring issue in SAP's October 2026 security updates, which included 16 new security notes and four GitHub advisories.
SAP Cloud SDK fixes and affected versions
SAP identifies SDK versions earlier than 0.45.2 as affected. Released August 21, 2026, version 0.45.2 introduced RFC 1123 DNS-label validation to restrict unsafe tenant-subdomain values in authentication URLs.
However, testing by The Hacker News found missing validation in versions 0.53.0 through 0.55.0, affecting certain Destination service authentication paths. All six releases failed nine of SAP's 11 validation tests.
Additional protection arrived in version 0.55.1. A separate change in version 0.58.3 addressed another tenant token URL injection issue. SAP has not formally classified the six intermediate releases as affected by CVE-2026-89111.
Organizations should prioritize these measures:
- Identify affected installations: Inventory
sap-cloud-sdkdependencies and check versions earlier than 0.45.2 and releases 0.53.0–0.55.0. - Apply updates and test fixes: Upgrade to a current corrected release and test whether malicious tenant values can redirect authentication requests.
- Restrict authentication traffic: Allowlist registered tenant subdomains and limit OAuth2 requests to approved identity-provider endpoints.
- Strengthen credential security: Enforce least privilege, protect application secrets, and maintain credential rotation procedures.
- Investigate suspicious activity: Review authentication and outbound connection logs. Revoke and rotate credentials if exposure is suspected.
- Test incident response plans: Exercise credential revocation, investigation, containment, and application recovery procedures.
A separate Coder registry compromise involving malicious Terraform modules illustrates how development infrastructure can also expose cloud credentials, although its attack mechanism differs from this flaw.
SAP recommends tenant-subdomain allowlisting when immediate patching is unavailable. Organizations should verify SDK versions and authentication paths while enforcing controls that limit credential exposure.
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