Security Resilience

CVE-2023-36893

Microsoft Outlook 2013 … 2016

Published
08 August 2023
Modified
10 August 2026
Patch / advisory
CVSS Score v3.1 6.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
EPSS Score 0.022 82th percentile
Risk Priority 58 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-36893 is a medium-severity Improper Input Validation (CWE-20) vulnerability in Microsoft Outlook. Its CVSS base score is 6.5 (Medium).

Operationally, ranked in the top 18% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

Microsoft Outlook contains a spoofing vulnerability tracked as CVE-2023-36893 that affects the client’s handling of incoming messages. The flaw received a CVSS 3.1 score of 6.5 with network attack vector, low complexity, no required privileges, and user-interaction requirements, resulting in high confidentiality impact while leaving integrity and availability untouched.

An unauthenticated remote attacker can deliver a specially crafted message that, once opened or previewed by the recipient, allows spoofed content to be presented, potentially exposing sensitive information from the victim’s mailbox or connected services. Exploitation therefore requires the target user to interact with the malicious message but does not need prior authentication or elevated privileges on the attacker’s part.

The Microsoft Security Response Center advisory at the referenced URL supplies the official patch and mitigation guidance. EPSS for the CVE rose from a low baseline to a peak of 0.0741 on 2025-01-22 before receding to the current value of 0.0092, indicating a period of increased exploitation interest after disclosure.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

Microsoft Outlook Spoofing Vulnerability

CWE(s)

Related Threats

CVEs Like This One

CVE-2025-47171Same product: Microsoft 365 Apps
CVE-2024-38021Same product: Microsoft 365 Apps
CVE-2023-36767Same product: Microsoft 365 Apps
CVE-2023-23397Same product: Microsoft 365 Apps
CVE-2023-36761Same product: Microsoft 365 Apps
CVE-2024-49033Same product: Microsoft 365 Apps
CVE-2023-36762Same product: Microsoft 365 Apps
CVE-2023-36897Same product: Microsoft 365 Apps
CVE-2024-38189Same product: Microsoft 365 Apps
CVE-2024-21413Same product: Microsoft 365 Apps

Affected Assets

microsoft
365 apps
all versions
microsoft
office
2019
microsoft
office long term servicing channel
2021
microsoft
outlook
2013, 2016

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-20

Security testing and developer training directly verify and enforce proper input validation, reducing exploitability of injection and malformed-data weaknesses.

addresses: CWE-20

Security testing and evaluation at multiple SDLC stages directly detects missing or flawed input validation, with the required remediation process ensuring fixes are applied.

addresses: CWE-20

Directly implements checks on information inputs to reject invalid data before processing.

addresses: CWE-20

Spam protection mechanisms perform filtering and detection on inbound/outbound messages, directly compensating for missing or weak input validation of unsolicited content.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

blocks

A.8.25 mandates security requirements, secure coding guidelines, checkpoints, testing (incl. code scans) and developer training in the SDLC, which reaches a slice of input validation defects but leaves the majority (incomplete enforcement, second-order inputs, parser differentials, post-validation canonicalization) unaddressed as in the SA-3 and A.8.28 anchors.

blocks

Mandating input controls that include integrity checks and input validation ensures that untrusted data is examined before use, blocking the root cause of many injection and malformed-data weaknesses.

blocks

Security-by-design principles explicitly call for data validation and sanitization at every layer, reducing the chance that malformed or malicious input will be processed without scrutiny.

prevents

Requiring language-specific secure coding standards, peer review, SAST and documented mitigation of common programming errors forces validation of all inputs before they are trusted.

finds

Testing against a defined set of requirements and using code review plus vulnerability scanning forces validation of inputs and handling of unanticipated conditions, reducing the chance that malformed data will be accepted.

Hardening callouts derived

DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.

  • No fine-grained STIG row for CWE-20, a class-level weakness, and none of its children carries one either.

References