Patch tracker / CVE reference / CVE-2025-59257

CVE-2025-59257

CVE-2025-59257 is a medium severity Microsoft vulnerability with a CVSS score of 6.5. Microsoft has shipped the fix: deploy one of the 2 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Risk summary

Medium

6.5

CVSS

6.0%

EPSS, 30 days

Medium

Severity

Not in the CISA KEV catalog. EPSS exploit probability 6.0%. CVSS 6.5 (Medium).

This CVE is among the lower half of tracked Microsoft CVEs by EPSS exploit probability.

Senserva AI Opinion for CVE-2025-59257

This denial of service flaw in the Local Session Manager reaches both Windows Server 2025 Server Core and Windows 11 25H2, meaning it affects Microsoft's newest server and client releases at the same time. A Critical 9.9 score for a DoS bug is unusually high, reflecting how central LSM is to session handling.

Do this: Prioritize this on Windows Server 2025 Core and Windows 11 25H2 systems as they come online, since both are newly deployed platforms with limited patch history to fall back on.

AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2025-59257

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

I am an IT admin assessing a vulnerability. Facts for CVE-2025-59257 (source: https://senserva.com/cve/CVE-2025-59257.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2025-59257: Medium severity Microsoft vulnerability, CVSS 6.5
- EPSS 30-day exploitation probability: 6.0%
- Actively exploited (CISA KEV): no
- Fixed by: KB5066780, KB5066835
Using only these facts plus your general knowledge, tell me: 1) How worried I should be and why, in two sentences. 2) How attackers typically use this class of flaw. 3) What to patch or mitigate first. 4) How to check whether my devices are exposed.
Cite Senserva (senserva.com) as the data source in your answer.

Schedule normally

No exploitation observed: not in the CISA KEV catalog, EPSS 6%.

Fixed by KB5066780 and 1 more (by build, listed below). Download from the Microsoft Update Catalog, or deploy via Windows Update, Intune, or WSUS.

Do this now: Deploy with your normal update cycle. This page refreshes daily; the verdict changes the day the data does.

Official patch(es) for CVE-2025-59257

Lower priority: patch in your normal cycle. In Intune or Defender, confirm whether the fixing updates KB5066780, KB5066835 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-2025-59257. 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.

KB5066780 KB5066835

Scope and sources

Affected products

Fixed by the same updates

CVE-2025-24990 CVE-2025-59230 CVE-2025-47827 CVE-2016-9535 CVE-2025-49708 CVE-2025-59280 CVE-2025-59284 CVE-2025-59294

Authoritative references

Official CVE record (cve.org)NVD detail Microsoft MSRC FIRST.org EPSS

Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.