CVE-2025-69871 in Medusa
Summary
by MITRE • 02/11/2026
A race condition vulnerability exists in MedusaJS Medusa v2.12.2 and earlier in the registerUsage() function of the promotion module. The function performs a non-atomic read-check-update operation when enforcing promotion usage limits. This allows unauthenticated remote attackers to bypass usage limits by sending concurrent checkout requests, resulting in unlimited redemptions of limited-use promotional codes and potential financial loss.
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Analysis
by VulDB Data Team • 02/13/2026
The vulnerability identified as CVE-2025-69871 represents a critical race condition flaw within the MedusaJS e-commerce platform version 2.12.2 and earlier. This issue specifically affects the promotion module's registerUsage() function, which is responsible for managing and enforcing usage limits on promotional codes. The race condition occurs due to improper synchronization mechanisms during concurrent access to shared resources, creating a window where multiple requests can simultaneously evaluate the same usage counter before any update occurs. This fundamental design flaw allows malicious actors to exploit the system's lack of atomic operations and manipulate promotional code redemption limits.
The technical implementation of this vulnerability stems from the registerUsage() function's failure to implement proper atomic operations when checking and updating usage counts for promotional codes. When multiple concurrent checkout requests arrive simultaneously, each request performs a read operation to check the current usage count, followed by a separate update operation to increment the counter. This non-atomic sequence creates a race condition where multiple requests can read the same initial value before any of them has updated the counter, leading to scenarios where the system incorrectly believes that the usage limit has not been reached despite multiple redemptions occurring. The vulnerability is classified under CWE-362, which specifically addresses race conditions in software implementations, and aligns with ATT&CK technique T1211 where adversaries exploit race conditions to bypass security controls.
The operational impact of this vulnerability extends beyond simple promotional code abuse to potentially cause significant financial loss for merchants utilizing the MedusaJS platform. Attackers can exploit this vulnerability to perform unlimited redemptions of limited-use promotional codes, effectively allowing them to claim discounts that should be restricted to specific usage limits. This could result in substantial revenue loss for businesses, particularly those offering high-value promotions or limited-time discounts. The unauthenticated nature of the attack means that no prior access or credentials are required, making it particularly dangerous as it can be exploited by anyone with access to the platform's checkout functionality. The vulnerability is especially concerning in high-traffic scenarios where concurrent requests are common, as the probability of successful exploitation increases with system load and request volume.
Mitigation strategies for CVE-2025-69871 should focus on implementing proper atomic operations within the registerUsage() function to ensure that read-check-update operations occur as single, indivisible units. Organizations should immediately upgrade to MedusaJS version 2.12.3 or later, which contains the patched implementation that resolves the race condition through proper synchronization mechanisms. Additionally, implementing database-level locks or using atomic update operations such as compare-and-swap mechanisms can prevent concurrent access issues. Security teams should also consider implementing rate limiting and monitoring for unusual promotional code redemption patterns to detect potential exploitation attempts. The fix should align with secure coding practices outlined in OWASP Top 10 and NIST guidelines for preventing race conditions in concurrent systems, ensuring that all shared resource access is properly synchronized to maintain data integrity and prevent unauthorized access to system controls.