CVE-2026-81521: The MongoDB Go Driver's client-level bulk write operation may accept a caller-supplied database name containin

Routine

MEDIUM 6.5UPGRADE

CVE-2026-81521 is a medium-severity flaw (CVSS 6.5) affecting go driver. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The MongoDB Go Driver's client-level bulk write operation may accept a caller-supplied database name containing a reserved separator character without escaping it before the name is used to build the target namespace for the operation. An application that passes untrusted input as a database name could therefore have the write directed at a database and collection other than the ones it intended. Only the Client.BulkWrite API is affected.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 86%)
CISA exploited list	No
Weakness	CWE-99
Published	2026-08-27
Last modified	2026-10-06

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

Last updated 2026-10-06 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-27 20:18 UTCPublished CVE record published
2026-10-06 19:18 UTCUpdated Record last modified

mongodb go driver UPGRADE

Affected: >= 2.1.0 and < 2.8.2

Fixed in: 2.8.2

Safe to downgrade to: a release before 2.1.0

1. Check installed version

apt-cache policy go-driver || rpm -q go-driver || go-driver --version

2. UPGRADE to 2.8.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade go-driver

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade go-driver

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 2.1.0 (Debian / Ubuntu)

apt-cache madison go-driver sudo apt install go-driver=<VERSION_BEFORE_2.1.0> sudo apt-mark hold go-driver

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

dnf --showduplicates list go-driver sudo dnf downgrade go-driver-<VERSION_BEFORE_2.1.0> sudo dnf versionlock add go-driver

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-2026-81521?

go driver: upgrade to 2.8.2. Exact commands for each OS are on this page.

Is CVE-2026-81521 being exploited?

CVE-2026-81521 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-2026-81521 affect?

CVE-2026-81521 affects go driver. Severity is medium (CVSS 6.5). The MongoDB Go Driver's client-level bulk write operation may accept a caller-supplied database name containing a reserved separator character without escaping it before the name is used to build the target namespace for the operation. An a

How urgent is CVE-2026-81521?

Priority 26/100. No elevated risk signals yet.

Software pages

MongoDB vulnerabilities

Related CVEs

CVE-2026-88031 HIGH 8.1 UPGRADE Improper neutralization of special elements in data query logic in the GridFS component of the MongoDB Go Driv

References

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