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NVD / CVE Program· CNA microsoft

CVE-2023-35311: Microsoft Outlook Security Feature Bypass Vulnerability

HighCVSS 8.8 · v3.1KEVWeaponized Fix available

Noroxi assessment

Priority: This week (action score 70/100)

  • CISA has confirmed exploitation in the wild (Jul 11, 2023). Remediation deadline for US federal agencies: Aug 1, 2023.
  • Probability of exploitation in the next 30 days: 15.5% (FIRST EPSS); higher than 96.8% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: Microsoft 365 Apps for Enterprise for 32-bit Systems https://aka.ms/OfficeSecurityReleases; Microsoft 365 Apps for Enterprise for 64-bit Systems https://aka.ms/OfficeSecurityReleases; Microsoft Office 2019 for 32-bit editions https://aka.ms/OfficeSecurityReleases.

Don’t wait for the next maintenance window. Upgrade to Microsoft 365 Apps for Enterprise for 32-bit Systems https://aka.ms/OfficeSecurityReleases; Microsoft 365 Apps for Enterprise for 64-bit Systems https://aka.ms/OfficeSecurityReleases; Microsoft Office 2019 for 32-bit editions https://aka.ms/OfficeSecurityReleases or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · CISA KEV · FIRST EPSS

Published
Jul 11, 2023
Updated
Oct 8, 2026
EPSS
15.5% · 96th percentile

Report tools

JSON

Action score

70

This week

Don’t wait for the next maintenance window.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
30 / 30 · Listed
EPSS
5 / 30 · 15.5%

CISA SSVC decision

Exploitation
active
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
8.8
CNA · microsoft
7.5
1.3 point gap

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Actively exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on Jul 11, 2023. That signals real attacks, not theory.

Remediation deadline for US federal agencies: Aug 1, 2023.

Get told when this record changes

  • In CISA KEV: exploitation in the wild confirmed
  • Weaponized exploit exists
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
microsoft365 apps
microsoftoffice 2019
microsoftoffice 2021
microsoftoutlook

Versions reported by the vendor

Affected version ranges reported by the assigning authority (microsoft). Independent of NVD's CPE analysis and usually ahead of it.

  • Microsoft Microsoft 365 Apps for Enterprise

    • 16.0.1 and later · before https://aka.ms/OfficeSecurityReleasesaffected

  • Microsoft Microsoft Office 2019

    • 19.0.0 and later · before https://aka.ms/OfficeSecurityReleasesaffected

  • Microsoft Microsoft Office LTSC 2021

    • 16.0.1 and later · before https://aka.ms/OfficeSecurityReleasesaffected

  • Microsoft Microsoft Outlook 2013

    • 14.0.0 and later · before 15.0.5571.1000affected

  • Microsoft Microsoft Outlook 2013 Service Pack 1

    • 15.0.0.0 and later · before 15.0.5571.1000affected

  • Microsoft Microsoft Outlook 2016

    • 16.0.0.0 and later · before 16.0.5404.1000affected
Affected versions · NVD (5)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • microsoft 365 appsall versions
  • microsoft office 2019all versions
  • microsoft office 2021all versions
  • microsoft outlook2013
  • microsoft outlook2016

Same product

microsoft: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-23397Microsoft Outlook Elevation of Privilege VulnerabilityKEV
    98Now
  • CVE-2024-21413Microsoft Outlook Remote Code Execution VulnerabilityKEV
    97Now
  • CVE-2026-21509Microsoft Office Security Feature Bypass VulnerabilityKEV
    82Now

Published before and after this one in the same product

  • ← EarlierCVE-2023-33161Jul 11, 2023 · Microsoft Excel Remote Code Execution Vulnerability
    31Monitor
  • ← EarlierCVE-2023-33162Jul 11, 2023 · Microsoft Excel Information Disclosure Vulnerability
    22Monitor
  • Later →CVE-2023-35371Aug 8, 2023 · Microsoft Office Remote Code Execution Vulnerability
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Microsoft 365 Apps for Enterprise for 32-bit Systemshttps://aka.ms/OfficeSecurityReleases · Click to RunMicrosoft (MSRC)
Microsoft 365 Apps for Enterprise for 64-bit Systemshttps://aka.ms/OfficeSecurityReleases · Click to RunMicrosoft (MSRC)
Microsoft Office 2019 for 32-bit editionshttps://aka.ms/OfficeSecurityReleases · Click to RunMicrosoft (MSRC)
Microsoft Office 2019 for 64-bit editionshttps://aka.ms/OfficeSecurityReleases · Click to RunMicrosoft (MSRC)
Microsoft Office LTSC 2021 for 32-bit editionshttps://aka.ms/OfficeSecurityReleases · Click to RunMicrosoft (MSRC)
Microsoft Office LTSC 2021 for 64-bit editionshttps://aka.ms/OfficeSecurityReleases · Click to RunMicrosoft (MSRC)
Microsoft Outlook 2013 (32-bit editions)15.0.5571.1000 · KB5002432Microsoft (MSRC)
Microsoft Outlook 2013 (64-bit editions)15.0.5571.1000 · KB5002432Microsoft (MSRC)
Microsoft Outlook 2013 RT Service Pack 115.0.5571.1000 · KB5002432Microsoft (MSRC)
Microsoft Outlook 2016 (32-bit edition)16.0.5404.1000 · KB5002427Microsoft (MSRC)
Microsoft Outlook 2016 (64-bit edition)16.0.5404.1000 · KB5002427Microsoft (MSRC)

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. CISA KEV-1 d
  2. Published
  3. TodayNov 14, 2026+1221 d

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-367 · Time-of-check Time-of-use (TOCTOU) Race Condition

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records