by Kastro
Paper/Archive/CVE-2026-55040

CVE-2026-55040

Microsoft Microsoft SharePoint Enterprise Server 2016 — Microsoft SharePoint Server Security Feature Bypass Vulnerability

KEV · due 21 AugEPSS 70%public exploitSSVC actCVSS 9.1
critical.is priorityof 100
97
CVSS 9.1 (CNA)9.1 / 10 × 3027.3In CISA KEV+3030.0EPSS percentile 99.4.994 × 2019.9Exploit: SSVC active+1010.0SSVC exploitation: active+1010.0
Description · from the CVE record

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

Affected

ProductAffectedFixed inSource
Microsoft SharePoint Enterprise Server 201616.0.0 – < 16.0.5561.100116.0.5561.1001CNA
Microsoft SharePoint Server 201916.0.0 – < 16.0.10417.2017516.0.10417.20175CNA
Microsoft SharePoint Server Subscription Edition16.0.0 – < 16.0.19725.2043416.0.19725.20434CNA

Scores by source

microsoft (CNA)9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C
CISA ADPSSVCExploitation: active · Automatable: yes · Technical impact: total

References

patchmsrc.microsoft.com/update-guide/vulnerability/CVE-2026-55040writeuprapid7.com/blog/post/ra-microsoft-sharepoint-jwt-token-authentication-bypass-cve-2026-55040exploitgithub.com/sfewer-r7/CVE-2026-55040refcisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-55040kevcisa.gov/known-exploited-vulnerabilities-catalog