CVE-2026-78509
Microsoft Office Outlook Remote Code Execution Vulnerability
Description
Heap-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.
INFO
Published Date :
Sept. 8, 2026, 6:20 p.m.
Last Modified :
Sept. 9, 2026, 4:20 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-78509
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | CRITICAL | [email protected] |
Solution
- Install vendor security updates promptly.
- Verify all systems are updated.
- Review security patch notes.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-78509.
| URL | Resource |
|---|---|
| https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78509 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-78509 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-78509
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-78509 vulnerability anywhere in the article.
-
CrowdStrike.com
September 2026 Patch Tuesday: Two Exploited Zero-Days and 113 Critical Vulnerabilities Among 972 CVEs
Microsoft has addressed 972 vulnerabilities in its September 2026 security update release, over double the number of CVEs released in August, and a new Patch Tuesday record. This month's patches inclu ... Read more
-
TheCyberThrone
Microsoft Patch Tuesday — September 2026
When Patch Volume Becomes a Security RiskMicrosoft’s September 2026 Patch Tuesday is not an ordinary monthly security update.Cybersecurity Trend ReportReleased on September 8, Microsoft addressed 974 ... Read more
The following table lists the changes that have been made to the
CVE-2026-78509 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 09, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-78509', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-04T00:00:00+00:00'} -
CVE Modified by [email protected]
Sep. 08, 2026
Action Type Old Value New Value Added Affected Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/78xxx/CVE-2026-78509.json">CVE-2026-78509</a> -
New CVE Received by [email protected]
Sep. 08, 2026
Action Type Old Value New Value Added Description Heap-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Added CWE CWE-122 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/78xxx/CVE-2026-78509.json">CVE-2026-78509</a> Added Reference https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78509