The disclosed CVE-2026-45659 deserialization flaw in SharePoint Server Subscription Edition, 2019, and 2016 grants remote code execution to any authenticated Site Member, bypassing the need for elevated privileges that typically gate such attacks. Microsoft’s advisory correctly flags the CVSS 8.8 rating yet understates the exposure surface: SharePoint remains the default collaboration platform for over 200,000 organizations worldwide, many of which retain legacy on-premises deployments long after support windows close. Prior incidents demonstrate the pattern. The in-the-wild exploitation of CVE-2026-32201 last month followed the same low-privilege vector, enabling initial access that threat actors chained into ransomware deployments within 72 hours according to Mandiant’s M-Trends 2025 report. Historical parallels with CVE-2023-29357 and ProxyShell further show that deserialization issues in SharePoint are rapidly productized by both state-linked groups and ransomware affiliates once proof-of-concept code appears on GitHub. Enterprise telemetry reveals the missed dimension: thousands of internet-facing SharePoint instances still permit external authentication without MFA or conditional access policies, creating direct network paths for the authenticated attacker Microsoft describes. Rapid weaponization risk is therefore not theoretical; the vulnerability’s minimal preconditions align precisely with observed attacker tradecraft that favors SharePoint as a persistent foothold rather than a one-time exploit. Organizations must prioritize patching within 48 hours and conduct immediate audits of Site Member permissions on externally reachable farms—steps the original coverage treats as routine rather than existential.