CVE-2026-18711: An issue in MongoDB Server's query execution engine could allow an authenticated user with read and write priv

Routine

HIGH 7.1UPGRADEDOWNGRADE

CVE-2026-18711 is a high-severity flaw (CVSS 7.1) 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's query execution engine could allow an authenticated user with read and write privileges to cause an internal reference to be used after the underlying memory has been freed, when running certain queries against time-series collections. This could result in a server crash or disclosure of freed memory contents within query results.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-416
Published	2026-08-11
Last modified	2026-09-25

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

Last updated 2026-09-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-11 19:17 UTCPublished CVE record published
2026-09-25 15:35 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: 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 8.0.29 (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-2026-18711?

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

Is CVE-2026-18711 being exploited?

CVE-2026-18711 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-2026-18711 affect?

CVE-2026-18711 affects mongodb, mongodb. Severity is high (CVSS 7.1). An issue in MongoDB Server's query execution engine could allow an authenticated user with read and write privileges to cause an internal reference to be used after the underlying memory has been freed, when running certain queries against

How urgent is CVE-2026-18711?

Priority 35/100. High severity

Software pages

MongoDB vulnerabilities

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References

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