CVE-2023-35311 KEV High · 8.8 EPSS 15.5%
Microsoft Outlook Security Feature Bypass Vulnerability
Microsoft · Outlook
Summary
A security feature bypass vulnerability in Microsoft Outlook, caused by a time-of-check to time-of-use (TOCTOU) race condition. An attacker on the network can exploit it without authentication or privileges, but a user must interact with a crafted item or message for the attack to succeed.
Heading is the official description · NVD
Priority scorePatchfirst’s 0 to 100 ranking. It adds points for CISA KEV listing, ransomware use, EPSS, threat reports, public exploit code and CVSS. Every CVE page shows the breakdown. Breakdown
63.5 / 100
- Exploited
- Yes, in CISA KEV
- Reports
- 0
- Tactics
- 2/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.How attackers get in
What they do
Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited the day it was disclosed.
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
2 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain order, 2 cited passages 2ExecutionTA0002
Malicious Link T1204.001 Medium Confidence (technique links)How sure Patchfirst is that an ATT&CK technique applies to this CVE. High and medium links are shown by default; low ones come from early or generic mappings, text matching, or contradict the CVE’s details.
AI mapping from the description · how it is exploited
User must interact with a crafted item
Microsoft Outlook Security Feature Bypass Vulnerability
Stealth
Exploitation for Stealth T1211 Medium Confidence (technique links)How sure Patchfirst is that an ATT&CK technique applies to this CVE. High and medium links are shown by default; low ones come from early or generic mappings, text matching, or contradict the CVE’s details.
AI mapping from the description · primary impact
Bypasses Outlook security feature controls
Microsoft Outlook Security Feature Bypass Vulnerability
Detection
0 rules for this CVE · 8 general rules for its techniquesRules for this CVE
0Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2023-35311 directly.CVE-specific rules are not available in this build. Search SigmaHQ ↗
General rules for this CVE’s techniques
These detect the technique in general, not this specific vulnerability.
Malicious LinkT1204.0014 general rules
- Symlink Etc Passwdhightest
- Potential ClickFix Execution Pattern - Registryhighexperimental
- Suspicious ClickFix/FileFix Execution Patternhighexperimental
- Suspicious Execution via macOS Script Editormediumtest
Exploitation for StealthT12114 general rules
- Audit CVE Eventcriticaltest
- Microsoft Malware Protection Engine Crashhightest
- Microsoft Malware Protection Engine Crash - WERhightest
- Writing Of Malicious Files To The Fonts Foldermediumtest
Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.
What security researchers reported
Not named in any threat report yetAlso mentioned in 50 community threat pulses (AlienVault OTX)
Weaker evidencePulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.
- Actively_Exploited_Kev | Oct 29, 202628 Oct 2026
- Actively_Exploited_Kev | Oct 28, 202627 Oct 2026
- Actively_Exploited_Kev | Oct 27, 202626 Oct 2026
- Actively_Exploited_Kev | Oct 24, 202623 Oct 2026
- Actively_Exploited_Kev | Oct 23, 202622 Oct 2026
- Actively_Exploited_Kev | Oct 22, 202621 Oct 2026
- 44 more on OTX