CISA KEV · Known exploitedHigh

CVE-2023-35311

Microsoft Outlook

CVE-2023-35311 affects Microsoft Outlook. Review the CVSS score, exploitation signals, affected versions, remediation status, and linked source material before making a change.

CVSS
7.5
EPSS
15.5%
96.5% percentile
CISA KEV
Listed
Published
2023.07.12
PRIORITY ASSESSMENT

Immediate review

CISA has listed this vulnerability in the Known Exploited Vulnerabilities catalog.

Known exploitationConfirmed by CISA KEV
Exploit probability15.5%
Technical severityCVSS 7.5

Vulnerability overview

CVE-2023-35311 affects Microsoft Outlook. Review the CVSS score, exploitation signals, affected versions, remediation status, and linked source material before making a change.

Affected product and versions

Product
Microsoft Outlook
Affected versions
16.0.1, 19.0.0, 16.0.0.0, 14.0.0, 15.0.0.0, 2019, 2021, 2013, 2016
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
CISA required action

Apply updates per vendor instructions or discontinue use of the product if updates are unavailable.

Due date: 2023.08.01
  1. 1
    Identify

    Confirm that Microsoft Outlook and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
CWE
CWE-367
KEV added
2023.07.11
Ransomware use
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