CVE-2023-35311
Microsoft Outlook Security Feature Bypass Vulnerability
Microsoft Outlook
Microsoft Outlook Security Feature Bypass Vulnerability
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 11 July 2023. US federal agencies were required to remediate it by 1 August 2023.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 15.5%, which is higher than 96.8% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Frequently asked questions
Is CVE-2023-35311 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2023-35311.
What does CVE-2023-35311 affect?
CVE-2023-35311 affects Microsoft Outlook. Microsoft Outlook Security Feature Bypass Vulnerability
How severe is CVE-2023-35311?
CVE-2023-35311 is rated HIGH with a CVSS base score of 8.8. EPSS puts the probability of exploitation in the next 30 days at 15.5%, higher than 96.8% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 1 August 2023.
How should organisations respond to CVE-2023-35311?
Apply the vendor patch for Microsoft Outlook as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.