Cybersource - Prosa Installments Service Disruption
KA-10751
13
06/03/2026 23:56 PM
1.0
Incident Date/Time
Start: 01 June 2026, 15:27 GMT
End: 03 June 2026, 00:23 GMT
Description of Issue
On 1st June 15:27 GMT, Cybersource experienced an issue following a recent release change whereby an unusually high rate of installment transactions began being declined by the Prosa processor for multiple merchant accounts during a high traffic period.
Impact
Some merchants may have observed elevated decline rates for installment transactions. Customers whose installment transactions were declined may have needed to retry their payments or use another payment method to complete their purchases. All other payment services outside Prosa continued to function normally.
Root Cause
Initial investigation indicates that the root cause was traced to a recent release change that introduced a technical inconsistency in how installment data was handled in the integration with the Prosa processor. Some installment transaction messages did not contain certain required installment information, causing Prosa’s system to interpret these transactions as incomplete and automatically decline them. This data formatting misalignment between Cybersource and Prosa’s installment processing functionality led to installment transactions being erroneously rejected.
Mitigating and Preventative Actions
To mitigate the incident, Cybersource’s technical teams disabled the newly introduced installment-related feature from the recent release (via configuration change), while keeping the core installment processing functionality enabled. This action immediately stopped further erroneous declines and restored normal transaction processing, including installment transactions, for impacted merchants.
To help prevent future recurrence, Cybersource plans to:
- Improve Data Validation and Testing: Enhance the validation controls and integration testing for the installment payment feature to ensure all required transaction data are properly transmitted to processing partners.
- Strengthen Monitoring and Alerts: Implement additional monitoring and real-time alerting focused on installment transaction flows and decline rate anomalies.
This incident was tracked and investigated under incident INC25861610 and EPS-38447.
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