CVE-2026-55040

Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.

CVSS v3.1

9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS

39.65% chance of exploitation in the next 30 days, 99th percentile

CISA KEV

added 2026-08-18

Nuclei

critical · CWE-1390

Published

2026-07-14

Updated

2026-08-31

Proof-of-concept exploits (5)

• l0ggg/CVE-2026-550403★ · 2026-07-28
• sfewer-r7/CVE-2026-5504058★ · 2026-08-10
• hypnguyen1209/CVE-2026-635201★ · 2026-08-26
• zenzue/CVE-2026-550400★ · 2026-08-26
• maxprog-svg/CVE-2026-55040-Mass-Exploit0★ · 2026-08-27

Nuclei templates (1)

• projectdiscovery/nuclei-templates/blob/main/javascript/cves/2026/CVE-2026-55040.yaml

References

• CVE Record
• NVD entry

Related

• CVE-2023-27532
• CVE-2023-34362
• CVE-2024-51977
• CVE-2024-51978
• CVE-2024-51979
• CVE-2024-51980