CVE-2026-18709: An issue in MongoDB Server could allow an authenticated user with direct network access to a shard to improper

Routine

MEDIUM 6.4UPGRADEDOWNGRADE

CVE-2026-18709 is a medium-severity flaw (CVSS 6.4) affecting mongodb, mongodb. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue in MongoDB Server could allow an authenticated user with direct network access to a shard to improperly commit or abort an in-progress prepared transaction, bypassing the intended transaction coordination process. This could result in cross-shard data inconsistency, cluster clock corruption, and violation of transaction atomicity guarantees.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.4 (Medium)
Attack vector	Adjacent network
Attack complexity	High
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 91%)
CISA exploited list	No
Weakness	CWE-862
Published	2026-08-11
Last modified	2026-10-23

Publisher (CNA): MongoDB, Inc. · Vendor: mongodb

Am I affected?

Timeline

2026-08-11 19:17 UTCPublished CVE record published
2026-10-23 21:10 UTCUpdated Record last modified

mongodb mongodb UPGRADE

Affected: >= 7.0.0 and < 7.0.40 · >= 8.0.0 and < 8.0.29 · >= 8.2.0 and <= 8.2.12 · >= 8.3.0 and < 8.3.8

Fixed in: 7.0.40, 8.0.29, 8.3.8

Safe to downgrade to: a release before 7.0.0

1. Check installed version

apt-cache policy mongodb || rpm -q mongodb || mongodb --version

2. UPGRADE to 7.0.40 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade mongodb

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade mongodb

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 7.0.0 (Debian / Ubuntu)

apt-cache madison mongodb sudo apt install mongodb=<VERSION_BEFORE_7.0.0> sudo apt-mark hold mongodb

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

dnf --showduplicates list mongodb sudo dnf downgrade mongodb-<VERSION_BEFORE_7.0.0> sudo dnf versionlock add mongodb

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.

mongodb mongodb DOWNGRADE

Affected: 9.0.0 alpha0 · 9.0.0 alpha1 · 9.1.0 alpha0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0.0

1. Check installed version

apt-cache policy mongodb || rpm -q mongodb || mongodb --version

2. No fixed release: DOWNGRADE to a release before 9.0.0 (Debian / Ubuntu)

apt-cache madison mongodb sudo apt install mongodb=<VERSION_BEFORE_9.0.0> sudo apt-mark hold mongodb

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list mongodb sudo dnf downgrade mongodb-<VERSION_BEFORE_9.0.0> sudo dnf versionlock add mongodb

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.

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-2026-18709?

mongodb: upgrade to 7.0.40, 8.0.29, 8.3.8; mongodb: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-18709 being exploited?

CVE-2026-18709 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-2026-18709 affect?

CVE-2026-18709 affects mongodb, mongodb. Severity is medium (CVSS 6.4). An issue in MongoDB Server could allow an authenticated user with direct network access to a shard to improperly commit or abort an in-progress prepared transaction, bypassing the intended transaction coordination process. This could result

How urgent is CVE-2026-18709?

Priority 25/100. No elevated risk signals yet.

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References

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