CVE-2026-50387: Stack-based buffer overflow in Windows GDI allows an authorized attacker to elevate privileges locally.

Q: How do I fix CVE-2026-50387?

365 copilot: mitigate or apply the listed mitigation; microsoft 365: mitigate or apply the listed mitigation; office 2021: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2026-50387 being exploited?

CVE-2026-50387 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-50387 affect?

CVE-2026-50387 affects 365 copilot, microsoft 365, office 2021. Severity is high (CVSS 7.8). Stack-based buffer overflow in Windows GDI allows an authorized attacker to elevate privileges locally.

Q: How urgent is CVE-2026-50387?

Priority 39/100. High severity; On your watchlist

Routine

HIGH 7.8WATCHLISTMITIGATEMITIGATEMITIGATE

CVE-2026-50387 is a high-severity flaw (CVSS 7.8) affecting 365 copilot, microsoft 365, office 2021. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Stack-based buffer overflow in Windows GDI allows an authorized attacker to elevate privileges locally.

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 74%)
CISA exploited list	No
Weakness	CWE-121
Published	2026-07-14
Last modified	2026-10-14

Publisher (CNA): Microsoft Corporation · Vendor: microsoft

Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-14 18:17 UTCPublished CVE record published
2026-10-14 22:10 UTCUpdated Record last modified

microsoft 365 copilot MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy 365-copilot || rpm -q 365-copilot || 365-copilot --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

microsoft microsoft 365 MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy microsoft-365 || rpm -q microsoft-365 || microsoft-365 --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

microsoft office 2021 MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy office-2021 || rpm -q office-2021 || office-2021 --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

microsoft office 2024 MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy office-2024 || rpm -q office-2024 || office-2024 --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

microsoft windows 10 1607 UPGRADE

Affected: < 10.0.14393.9339

Fixed in: 10.0.14393.9339

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

microsoft windows 10 1809 UPGRADE

Affected: < 10.0.17763.9020

Fixed in: 10.0.17763.9020

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-50387?

365 copilot: mitigate or apply the listed mitigation; microsoft 365: mitigate or apply the listed mitigation; office 2021: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-50387 being exploited?

CVE-2026-50387 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-50387 affect?

CVE-2026-50387 affects 365 copilot, microsoft 365, office 2021. Severity is high (CVSS 7.8). Stack-based buffer overflow in Windows GDI allows an authorized attacker to elevate privileges locally.

How urgent is CVE-2026-50387?

Priority 39/100. High severity; On your watchlist

Software pages

Windows vulnerabilities · Microsoft Office vulnerabilities

Related CVEs

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CVE-2026-41614 MEDIUM 6.2 UPGRADE Improper access control in M365 Copilot for Desktop allows an unauthorized attacker to perform spoofing locall
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References

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