# Microsoft Office Remote Code Execution Vulnerability

CVE record · `CVE-2026-55049`

- **Identifiers:** `CVE-2026-55049`
- **State:** Confirmed
- **Severity:** CVSS 7.8 High
- **Critical:** No
- **CNA:** microsoft
- **Weakness (CWE):** [CWE-122](https://cwe.mitre.org/data/definitions/122.html)
- **Tags:** [Memory corruption](https://agentprime.io/advisories/tag/memory-corruption.md)
- **Technologies:** [Microsoft 365 Apps for Enterprise](https://agentprime.io/advisories/technology/microsoft-365-apps-for-enterprise.md) · [Microsoft Office 2016](https://agentprime.io/advisories/technology/microsoft-office-2016.md) · [Microsoft Office 2019](https://agentprime.io/advisories/technology/microsoft-office-2019.md) · [Microsoft Office 365 for Mac](https://agentprime.io/advisories/technology/microsoft-office-365-for-mac.md) · [Microsoft Office LTSC 2021](https://agentprime.io/advisories/technology/microsoft-office-ltsc-2021.md) · [Microsoft Office LTSC 2024](https://agentprime.io/advisories/technology/microsoft-office-ltsc-2024.md) · [Microsoft Office LTSC for Mac 2021](https://agentprime.io/advisories/technology/microsoft-office-ltsc-for-mac-2021.md) · [Microsoft Office LTSC for Mac 2024](https://agentprime.io/advisories/technology/microsoft-office-ltsc-for-mac-2024.md)
- **Published:** 14 Jul 2026
- **Updated:** 1 Nov 2026
- **Reviewed by a person:** No

Published by the CVE Program (CNA: microsoft) at 14 Jul 2026, 17:08 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

## Affected products, as the CNA wrote them

- Vendor: Microsoft. Product: Microsoft 365 Apps for Enterprise.
  - affected: `16.0.1 to before https://aka.ms/OfficeSecurityReleases` (custom)
- Vendor: Microsoft. Product: Microsoft Office 2016.
  - affected: `16.0.0 to before 16.0.5561.1000` (custom)
- Vendor: Microsoft. Product: Microsoft Office 2019.
  - affected: `19.0.0 to before https://aka.ms/OfficeSecurityReleases` (custom)
- Vendor: Microsoft. Product: Microsoft Office 365 for Mac.
  - affected: `1.0.0 to before 16.111.26071215` (custom)
- Vendor: Microsoft. Product: Microsoft Office LTSC 2021.
  - affected: `16.0.1 to before https://aka.ms/OfficeSecurityReleases` (custom)
- Vendor: Microsoft. Product: Microsoft Office LTSC 2024.
  - affected: `16.0.0 to before https://aka.ms/OfficeSecurityReleases` (custom)
- Vendor: Microsoft. Product: Microsoft Office LTSC for Mac 2021.
  - affected: `16.0.1 to before 16.111.26071215` (custom)
- Vendor: Microsoft. Product: Microsoft Office LTSC for Mac 2024.
  - affected: `16.0.0 to before 16.111.26071215` (custom)

## Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

## Severity and exploitation

- 7.8 High, CVSS 3.1: `CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C`, from CNA (microsoft)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0047, the 40th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 14 Jul 2026, 17:08 UTC: [Confirmed by the CVE List](https://www.cve.org/CVERecord?id=CVE-2026-55049)

## Sources

- [CVE List: CVE-2026-55049](https://www.cve.org/CVERecord?id=CVE-2026-55049)
- [NVD: CVE-2026-55049](https://nvd.nist.gov/vuln/detail/CVE-2026-55049)

### References from the CNA

- <https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55049> (vendor-advisory, patch)

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.

## Check whether this affects you

This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it. Compare the affected versions above with what you run.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), `get_advisory` returns this record and `search_advisories` finds related ones. Setup: <https://agentprime.io/mcp.md>
- As JSON: <https://api.agentprime.io/v1/advisories/CVE-2026-55049>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-55049/>. Everything for agents: <https://agentprime.io/llms.txt>.