cloud-security-services-integration-library CVE-2026-89105

Exploitation requires the affected application to be bound to multiple IAS/XSUAA service instances so that an 'ambient' binding exists whose tokens the HybridTokenAuthenticator will accept despite not being the intended trust source; single-binding deployments are not affected. The attacker must already possess a valid token minted by such an ambient binding (PR:L), and must navigate the non-default multi-binding topology (AC:H), which limits exploitation to specific SAP BTP Cloud Foundry configurations rather than default single-tenant setups. Impact is bounded to low confidentiality and integrity with no availability effect.

All available signals point to a genuinely low-priority issue rather than an urgent one. The vendor-supplied CVSS:3.1 vector (AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N) scores 4.2 (Medium): network-reachable but high attack complexity, requiring the attacker to already hold low-level privileges (a valid token from an ambient binding) and yielding only low confidentiality and integrity impact with no availability impact. No EPSS score was provided in the input, so exploitation probability cannot be quantified. The CVE is not listed in CISA KEV and no public exploit code was referenced, so this is no public exploit identified at time of analysis. No SSVC decision data was supplied. The signals are internally consistent - there is no network-vs-local contradiction and no KEV-vs-EPSS conflict - which reinforces that this is a defense-in-depth hardening fix (CWE-1188, insecure default initialization) disclosed by SAP itself, not a high-urgency flaw. The main caveat is that the 'Authentication Bypass' tag overstates impact: the PR:L vector confirms the attacker must already possess a token, so this is a token-scope/trust-boundary weakness, not a full unauthenticated bypass.

In an SAP BTP environment where an application is bound to multiple IAS/XSUAA service instances, an attacker who already holds a valid token issued by one ambient binding presents it to an application that should only trust a different, intended binding. Because the HybridTokenAuthenticator accepts the token from the unintended binding, the attacker gains access to resources they were not authorized for. No public proof-of-concept was referenced, and the high attack complexity means the attacker must understand the specific multi-binding configuration to succeed.