Patch tracker / CVE reference / CVE-2026-45504
CVE-2026-45504
CVE-2026-45504 is a high severity Microsoft vulnerability with a CVSS score of 8.8. Its EPSS score puts the probability of exploitation in the next 30 days at 20%. Microsoft has shipped the fix: deploy one of the 4 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.
Risk summary
Not in the CISA KEV catalog. EPSS exploit probability 20%. CVSS 8.8 (High).
This CVE is among the lower half of tracked Microsoft CVEs by EPSS exploit probability.
The strongest signal is EPSS, which climbed from 5.6% on 2026-07-17 to 20.3% on 2026-07-24 and then jumped to 70.3% on 2026-08-03. Meanwhile CVSS Severity rose from 8.8 to 9.6 on 2026-07-29. Both exploit likelihood and Severity are trending sharply upward, so prioritize patching this today.
Drawn by Senserva Vivid from the Senserva change record. Hover any point for its date and value.
- 2026-07-17 EPSS first scored at 5.6%
- 2026-07-24 EPSS 5.6% to 20.3%
- 2026-07-29 CVSS 8.8 to 9.6
- 2026-08-03 EPSS 20.3% to 70.3%
Recorded by Senserva on the dates shown, from CISA KEV and FIRST EPSS. This is what moved and when, which neither the vendor advisory nor NVD publishes.
This is a High severity (CVSS 8.8) elevation of privilege flaw in Microsoft Exchange Server, hitting on-premises Exchange running Subscription Edition RTM, 2019 Cumulative Update 15, and 2016 Cumulative Update 23. Exchange privilege escalation is high value because a foothold on a mailbox server can lead to domain wide compromise, though this one is not in CISA KEV and EPSS puts exploitation likelihood at 6 percent. Cloud only Exchange Online tenants are not affected; this is strictly an on-prem server concern.
Do this: Apply the current Microsoft security update to your affected Exchange 2016 CU23, 2019 CU15, and Subscription Edition RTM servers, confirming the required cumulative update baseline is in place first.
AI-generated from public data, 2026-07-22. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2026-45504
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Official patch(es) for CVE-2026-45504
Elevated priority: high severity or a meaningful exploitation probability, sooner if an affected product is internet-facing. In Intune or Defender, confirm whether the fixing updates KB5103212, KB5103213, KB5103214, KB5103215 are installed across the affected products. Senserva does this automatically across your tenant and flags every missing patch.
Apply the Microsoft security updates below to fix CVE-2026-45504. Each KB page carries the Microsoft Update Catalog download, Microsoft's known issues for the update, a copy-paste PowerShell check for whether it is installed, and the Senserva AI read.
Scope and sources
- Affected products
- Fixed by the same updates
- Authoritative references
Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.