CVE-2026-40420Disclosure(microsoft / 365_apps)

LOWCVSS 8.8 · HIGH

Signal is active with 1 mentions in latest observed window

Immediate actions

Track advisory updates for patch or workaround availability

Recommended action window: Monitor and triage in normal cycle

NVD description

Use after free in Microsoft Office allows an authorized attacker to elevate privileges locally.

microsoft CVEs Back to dashboard

0.0/ 10 priority

Sources & remediation

Vendor / third-party advisories

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40420

Weakness type (CWE)

CWE-284

Priority

LOW

Exploitation

NONE

PoC

NONE

Patch

NONE

Momentum

NONE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

365_apps
office
office_long_term_servicing_channel

Threat summary

1 mentions across 1 observed day

What's happening

Technical details provided in 1 signal
Disclosure: 1 classified signal
1 total mentions across 1 day

Affected systems

Vendors

microsoft

Products

365_appsofficeoffice_long_term_servicing_channel

4 versions affected across 3 products

Deep dive

Activity timeline1 mentions / 1d

Signal classification1 categories

Disclosure

1100.0%

Referenced assets1 URL

By indicator

https://windowsforum.com/threads/cve-2026-40420-microsoft-office-click-to-run-privilege-escalation-to-system.417987/?utm_source=x&utm_medium=social&utm_campaign=news_node84

Full discourse1 post

WindowsForum@windowsforum148d
Disclosure
🚨 Office Click-To-Run gets a SYSTEM privilege boost (CVE-2026-40420). “Less likely” is cute—local attackers don’t need a script kiddie lottery, they need one foothold. #Windows #Security https://windowsforum.com/threads/cve-2026-40420-microsoft-office-click-to-run-privilege-escalation-to-system.417987/?utm_source=x&utm_medium=social&utm_campaign=news_node84 #MicrosoftOffice #PrivilegeEscalation #Cve202640420 #ClickToRun https://t.co/1pi8SeAL1q
Post summary
The tweet announces Microsoft Office Click-To-Run CVE‑2026‑40420 as a privilege‑escalation flaw that can elevate to SYSTEM, with no PoC, active exploitation, or patch discussed.
0000028
1.1K followersView on X

CPE platform detail8 entries

Part:

Vendor:

Product:

Version:

Target SW:

Target HW:

8 of 8 entries

Part	Vendor	Product	Version	Target SW	Target HW
App	microsoft	365_apps	-	-	x64
App	microsoft	365_apps	-	-	x86
App	microsoft	office	2019	-	x64
App	microsoft	office	2019	-	x86
App	microsoft	office_long_term_servicing_channel	2021	-	x64
App	microsoft	office_long_term_servicing_channel	2021	-	x86
App	microsoft	office_long_term_servicing_channel	2024	-	x64
App	microsoft	office_long_term_servicing_channel	2024	-	x86

Explore more

Back to dashboard microsoft CVEs 365_apps vulnerabilities