---
id: "CVE-2023-35311"
kind: "vulnerability"
aliases: ["CVE-2023-35311"]
title: "Microsoft Outlook Security Feature Bypass Vulnerability"
severity: "high"
cvss: 8.8
epss: null
exploited: true
status: "open"
category: "vendor"
products: [{"name": "Microsoft Outlook", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft 365 apps", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft office 2019", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft office 2021", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft outlook", "fixed": [], "affected": "= 2013", "ecosystem": "vendor"}, {"name": "microsoft outlook", "fixed": [], "affected": "= 2016", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "microsoft-outlook", "vendor", "windows"]
not_affected_if: ["unknown"]
published_at: "2023-07-11T00:00:00+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-23T22:29:04+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2023-35311", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-35311", "first_seen_at": "2026-10-23T22:29:04+00:00"}]
---

# Microsoft Outlook Security Feature Bypass Vulnerability

Microsoft Outlook has a security feature bypass that lets an attacker skip the Outlook Security Notice prompt. CISA lists it as actively exploited, and the sources give no further detail on what the attacker gets after the bypass.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Microsoft Outlook affected ? fixed ?
- vendor:microsoft 365 apps affected ? fixed ?
- vendor:microsoft office 2019 affected ? fixed ?
- vendor:microsoft office 2021 affected ? fixed ?
- vendor:microsoft outlook affected = 2013 fixed ?
- vendor:microsoft outlook affected = 2016 fixed ?

## Fix

Apply Microsoft's updates for Outlook per the vendor instructions, or stop using the product if no update is available (CISA required action).

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2023-35311
- 2026-10-23T22:29:04+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2023-35311

## From the sources

Microsoft Outlook contains a security feature bypass vulnerability that allows an attacker to bypass the Microsoft Outlook Security Notice prompt.

CISA required action: Apply updates per vendor instructions or discontinue use of the product if updates are unavailable.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_