CVE-2026-55040
CRITICALCVSS 9.1/10EPSS 0.68%
Last modified
CVE-2026-55040 is a critical-severity vulnerability rated 9.1/10 on the CVSS scale. Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.. EPSS estimates a 0.68% chance of exploitation in the next 30 days.
Description
Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Sharepoint Server | < 16.0.19725.20434 |
| Microsoft | Sharepoint Server | 2016 |
| Microsoft | Sharepoint Server | 2019 |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55040Patch, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-55040?
Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.
How severe is CVE-2026-55040?
CVE-2026-55040 has a CVSS score of 9.1/10 (CRITICAL severity). The EPSS model estimates a 0.68% probability of exploitation in the next 30 days.
How do I fix CVE-2026-55040?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
Related CVEs from 2026
- CVE-2026-55035Out-of-bounds read in Microsoft Office allows an unauthorize…3.3
- CVE-2026-55036Buffer over-read in Microsoft Office Excel allows an unautho…7.8
- CVE-2026-55037Heap-based buffer overflow in Microsoft Office Excel allows …7.8
- CVE-2026-55038Stack-based buffer overflow in Microsoft Office Word allows …7.8
- CVE-2026-55039Integer underflow (wrap or wraparound) in Microsoft Office E…7.8
- CVE-2026-5504A padding oracle exists in wolfSSL's PKCS7 CBC decryption th…5.3
- CVE-2026-55041Heap-based buffer overflow in Microsoft Office Excel allows …7.8
- CVE-2026-55042Use of uninitialized resource in Microsoft Office allows an …5.5
- CVE-2026-55043Heap-based buffer overflow in Microsoft Office PowerPoint al…7.8
- CVE-2026-55044Out-of-bounds read in Microsoft Office Excel allows an unaut…7.8
- CVE-2026-55045Out-of-bounds read in Microsoft Office allows an unauthorize…8.4
- CVE-2026-55046Out-of-bounds read in Microsoft Office Excel allows an unaut…5.5
Are you affected by CVE-2026-55040?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST