CVE•Published 2026-07-24•Modified 2026-07-29•1 article on news•4 live references•NVD data

CVE-2026-56191Microsoft · Exchange_online

Vulnerability data via NVD (ingested)

CVSS v3.1

10.0

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS percentile

Exploit Prediction Scoring System · top 51% of all CVEs

Weaknesses (CWE)

CWE-287Improper Authentication

Description

Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.

Timeline

Published 2026-07-24

Modified 2026-07-29

External references

NVD MITRE Exploit-DB VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag0 hosts

vuln:CVE-2026-56191

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"Microsoft Exchange Online"

All exposed Microsoft Exchange Online instances — cross-reference with the CVE's affected-version range.

Shodan · banner/body mention

http.html:"Exchange Online"

HTTP body or banner mentions "Exchange Online" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2026-56191

Country / ASN / product breakdown for the vuln query.

Censys

vulnerabilities.cve_id: CVE-2026-56191

Censys host search filtered to this CVE id.

grep.app

CVE-2026-56191

Public source-code mentions — fast PoC discovery.

GitHub code

CVE-2026-56191

GitHub code search for direct mentions.

Google dork

"CVE-2026-56191" exploit -site:nvd.nist.gov

Write-ups and news, NVD excluded.

Known PoCs on GitHub

No public proof-of-concept repositories found for CVE-2026-56191 on GitHub.