Microsoft Outlook Security Feature Bypass Vulnerability
- Published
- Jul 11, 2023
- Updated
- Jun 17, 2026
- EPSS
- 15.5% · 97th percentile
- CWE
- CWE-367
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Report tools
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
- —
- CNA · microsoft
- 8.8
- NVD has not scored this yet; the score shown is the CNA’s.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
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 government agencies: Aug 1, 2023.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| microsoft | 365 apps | cpe:2.3:a:microsoft:365_apps |
| microsoft | office | cpe:2.3:a:microsoft:office |
| microsoft | office long term servicing channel | cpe:2.3:a:microsoft:office_long_term_servicing_channel |
| microsoft | outlook | cpe:2.3:a:microsoft:outlook |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- microsoft 365 appsall versions
- microsoft office2019
- microsoft office long term servicing channel2021
- microsoft outlook2013
- microsoft outlook2016
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
Same product
microsoft: all recordsOther highest-scoring records for the same primary product.
- CVE-2023-23397Microsoft Outlook Elevation of Privilege VulnerabilityKEV98Now
- CVE-2024-21413Microsoft Outlook Remote Code Execution VulnerabilityKEV97Now
- CVE-2026-21509Microsoft Office Security Feature Bypass VulnerabilityKEV82Now
- CVE-2021-42292Microsoft Excel Security Feature Bypass VulnerabilityKEV74This week
- CVE-2024-38189Microsoft Project Remote Code Execution VulnerabilityKEV67This week
- CVE-2023-21715Microsoft Publisher Security Feature Bypass VulnerabilityKEV63This week
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
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.
- CISA KEV-1 d
- Published
- TodaySep 29, 2026+1176 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
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 ConditionCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
- msrc.microsoft.com/update-guide/vulnerability/CVE-2023-35311
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-35311
Vendor advisories and official records. Exploit/PoC links are deliberately left out.