CVE-2026-84963: An incorrect numeric conversion in the JSON parsing component of the MongoDB C Driver's BSON library may cause

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2026-84963 is a medium-severity flaw (CVSS 5.3) affecting c driver. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An incorrect numeric conversion in the JSON parsing component of the MongoDB C Driver's BSON library may cause an unusually large text value to be silently shortened, or the corresponding field to be omitted, while the parsing operation still reports success and returns no error. An unauthenticated party who can supply the input processed by an application that uses this component may cause that application to hold data that does not match what w

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 76%)
CISA exploited list	No
Weakness	CWE-681
Published	2026-09-03
Last modified	2026-09-22

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

Last updated 2026-09-22 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-03 16:18 UTCPublished CVE record published
2026-09-22 16:22 UTCUpdated Record last modified

mongodb c driver UPGRADE

Affected: >= 1.10.0 and < 1.30.9 · >= 2.0.0 and < 2.5.2

Fixed in: 1.30.9, 2.5.2

Safe to downgrade to: a release before 1.10.0

1. Check installed version

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

2. UPGRADE to 1.30.9 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade c-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 1.10.0 (Debian / Ubuntu)

apt-cache madison c-driver sudo apt install c-driver=<VERSION_BEFORE_1.10.0> sudo apt-mark hold c-driver

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

dnf --showduplicates list c-driver sudo dnf downgrade c-driver-<VERSION_BEFORE_1.10.0> sudo dnf versionlock add c-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-2026-84963?

c driver: upgrade to 1.30.9, 2.5.2. Exact commands for each OS are on this page.

Is CVE-2026-84963 being exploited?

CVE-2026-84963 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-2026-84963 affect?

CVE-2026-84963 affects c driver. Severity is medium (CVSS 5.3). An incorrect numeric conversion in the JSON parsing component of the MongoDB C Driver's BSON library may cause an unusually large text value to be silently shortened, or the corresponding field to be omitted, while the parsing operation sti

How urgent is CVE-2026-84963?

Priority 29/100. Remotely exploitable, no login, no user action

Software pages

MongoDB vulnerabilities

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References

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