CVE-2026-67643: Heap-based buffer overflow in SQL Server allows an unauthorized attacker to execute code over a network.

This week

CRITICAL 9.8REMOTEWATCHLISTUPGRADEUPGRADE

CVE-2026-67643 is a critical-severity flaw (CVSS 9.8) affecting sql server 2022, sql server 2025. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Heap-based buffer overflow in SQL Server allows an unauthorized attacker to execute code over a network.

Why this priority

Critical severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.0% (top 38%)
CISA exploited list	No
Weakness	CWE-122
Published	2026-09-08
Last modified	2026-09-17

Publisher (CNA): Microsoft Corporation · Vendor: microsoft

Last updated 2026-09-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-08 18:18 UTCPublished CVE record published
2026-09-17 20:17 UTCUpdated Record last modified

microsoft sql server 2022 UPGRADE

Affected: < 16.0.1200.5 · >= 16.0.4003.1 and < 16.0.4275.2

Fixed in: 16.0.1200.5, 16.0.4275.2

Safe to downgrade to: a release before 16.0.4003.1

1. Check installed version

apt-cache policy sql-server-2022 || rpm -q sql-server-2022 || sql-server-2022 --version

2. UPGRADE to 16.0.1200.5 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade sql-server-2022

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade sql-server-2022

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 16.0.4003.1 (Debian / Ubuntu)

apt-cache madison sql-server-2022 sudo apt install sql-server-2022=<VERSION_BEFORE_16.0.4003.1> sudo apt-mark hold sql-server-2022

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list sql-server-2022 sudo dnf downgrade sql-server-2022-<VERSION_BEFORE_16.0.4003.1> sudo dnf versionlock add sql-server-2022

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

microsoft sql server 2025 UPGRADE

Affected: < 17.0.1135.8 · >= 17.0.4006.2 and < 17.0.4085.5

Fixed in: 17.0.1135.8, 17.0.4085.5

Safe to downgrade to: a release before 17.0.4006.2

1. Check installed version

apt-cache policy sql-server-2025 || rpm -q sql-server-2025 || sql-server-2025 --version

2. UPGRADE to 17.0.1135.8 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade sql-server-2025

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade sql-server-2025

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 17.0.4006.2 (Debian / Ubuntu)

apt-cache madison sql-server-2025 sudo apt install sql-server-2025=<VERSION_BEFORE_17.0.4006.2> sudo apt-mark hold sql-server-2025

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list sql-server-2025 sudo dnf downgrade sql-server-2025-<VERSION_BEFORE_17.0.4006.2> sudo dnf versionlock add sql-server-2025

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Fedora ELN · xfsdump · FIXED · 3.3.0-3.eln159 · FEDORA-2026-6e9bb3f901 · source

sudo dnf upgrade --advisory=FEDORA-2026-6e9bb3f901

Fedora 46 · fio · FIXED · 3.43-2.fc46 · FEDORA-2026-b36219886b · source

sudo dnf upgrade --advisory=FEDORA-2026-b36219886b

Microsoft SQL Server 2022 for x64-based Systems (GDR) · KB5122771 · FIXED · 16.0.1200.5 · KB5122771 · source

Install KB5122771 via Windows Update, then verify: Get-HotFix -Id KB5122771

Microsoft SQL Server 2025 for x64-based Systems (GDR) · KB5122770 · FIXED · 17.0.1135.8 · KB5122770 · source

Install KB5122770 via Windows Update, then verify: Get-HotFix -Id KB5122770

Microsoft SQL Server 2022 for x64-based Systems (CU 26) · KB5122768 · FIXED · 16.0.4275.2 · KB5122768 · source

Install KB5122768 via Windows Update, then verify: Get-HotFix -Id KB5122768

Microsoft SQL Server 2025 for x64-based Systems (CU8) · KB5122769 · FIXED · 17.0.4085.5 · KB5122769 · source

Install KB5122769 via Windows Update, then verify: Get-HotFix -Id KB5122769

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-2026-67643?

sql server 2022: upgrade to 16.0.1200.5, 16.0.4275.2; sql server 2025: upgrade to 17.0.1135.8, 17.0.4085.5. Exact commands for each OS are on this page.

Is CVE-2026-67643 being exploited?

CVE-2026-67643 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-2026-67643 affect?

CVE-2026-67643 affects sql server 2022, sql server 2025. Severity is critical (CVSS 9.8). Heap-based buffer overflow in SQL Server allows an unauthorized attacker to execute code over a network.

How urgent is CVE-2026-67643?

Priority 60/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Microsoft SQL Server vulnerabilities

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References

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