CVE-2025-8396: Temporal OSS Server

Medium severity, CVSS 6.9. EPSS: 0.4% chance of exploitation in the next 30 days.

Insufficiently specific bounds checking on authorization header could lead to denial of service in the Temporal server on all platforms due to excessive memory allocation.This issue affects all platforms and versions of OSS Server prior to 1.26.3, 1.27.3, and 1.28.1 (i.e., fixed in 1.26.3, 1.27.3, and 1.28.1 and later). Temporal Cloud services are not impacted.

Affected products

• Temporal OSS Server: before 1.26.3 (fixed in 1.26.3); from 1.27.0, before 1.27.3 (fixed in 1.27.3); from 1.28.0, before 1.28.1 (fixed in 1.28.1)

Published 2025-09-15. Last modified 2026-06-17.