CVE•Published 2026-01-26•Modified 2026-06-25•3 articles on news•6 live references•NVD data

CVE-2026-21509Microsoft · 365_apps

Vulnerability data via NVD (ingested)

CVSS v3.1

7.8

HIGH

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

EPSS percentile

Exploit Prediction Scoring System · top 1% of all CVEs

Weaknesses (CWE)

CWE-807Reliance on Untrusted Inputs in a Security Decision

Description

Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.

Timeline

Published 2026-01-26

Modified 2026-06-25

External references

NVD MITRE Exploit-DB Sploitus trickest/cve 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-2026-21509

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"Microsoft 365 Apps"

All exposed Microsoft 365 Apps instances — cross-reference with the CVE's affected-version range.

Shodan · banner/body mention

http.html:"365 Apps"

HTTP body or banner mentions "365 Apps" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2026-21509

Country / ASN / product breakdown for the vuln query.

Censys

vulnerabilities.cve_id: CVE-2026-21509

Censys host search filtered to this CVE id.

grep.app

CVE-2026-21509

Public source-code mentions — fast PoC discovery.

GitHub code

CVE-2026-21509

GitHub code search for direct mentions.

Google dork

"CVE-2026-21509" exploit -site:nvd.nist.gov

Write-ups and news, NVD excluded.

Known PoCs on GitHub (8)

CVE-2026-215098 repos

GhostTroops/TOPShell

TOP All bugbounty pentesting CVE-2023- POC Exp RCE example payload Things

★ 732·updated today

i014n/RightHand-PersistenceC++

COM Windows Persistence Technique

★ 88·updated 1mo ago

DarkFunct/TK-CVE-RepoPython

TK-CVE-Repo

★ 51·updated 2w ago

Xuchen-Li/cv-arxiv-dailyPython

Automatically update arXiv papers about SOT & VLT, Multi-modal Learning, LLM and Video Understanding using Github Actions.

★ 47·updated 3d ago

XuzhaoLi/ro-arxiv-dailyPython

Automatically Update Arxiv Papers about Path Planning, LLM and Autonomous Driving using Github Actions since 2024.2.

★ 37·updated 3d ago

gavz/CVE-2026-21509-PoCunknown

Educational PoC for CVE‑2026‑21509 (Microsoft Office security feature bypass). Generates a harmless DOCX with dummy OLE artifacts to study EDR/AV visibility. Not an exploit. For is…

★ 17·updated 4mo ago

zulloper/cve-pocPython

CVE POC repo 자동 수집기

★ 14·updated today

kimstars/Ashwesker-CVE-2026-21509unknown

CVE-2026-21509

★ 10·updated 4mo ago