Threats / Microsoft / CVE-2023-35311
CVE-2023-35311
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft Outlook vulnerability
Microsoft Outlook security feature bypass vulnerability allows attackers to circumvent the Security Notice prompt, potentially enabling unauthorized access to sensitive email content or execution of malicious actions.
Verdict
Today item — known-exploited.
A security feature bypass in Outlook that undermines the Security Notice prompt protection mechanism. Active exploitation in the wild indicates practical threat; however, the vulnerability requires user interaction and specific conditions to be effective.
CISA KEV Yes · 2023-07-115EPSS 0.15522 (verify live)6CVSS 8.83CISA SSVC Exploitation: active · Automatable: no · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
3 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-07-11).
Probability (EPSS)
EPSS 0.15522 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 8.8 (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) · Affected: Microsoft, Outlook. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
Weakness (CWE)
Mapped to CWE-367 TOCTOU Race Condition.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog the same day the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
WeaknessCWE-367 · TOCTOU Race Condition
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious email or attachment designed to trigger the Security Notice prompt, then exploit the bypass to proceed without user awareness.
Business
Email security controls fail to protect against phishing, malware delivery, or social engineering attacks that would normally be flagged by security warnings.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I bypass the security prompt to execute embedded scripts or access restricted email content that the prompt was designed to prevent.
Business
Sensitive corporate communications, credentials, or intellectual property become accessible to unauthorized parties despite security policies.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05