CVE-2026-84969: A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small numbe

Routine

LOW 3.7REMOTEUPGRADE

CVE-2026-84969 is a low-severity flaw (CVSS 3.7) affecting c driver. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	3.7 (Low)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 81%)
CISA exploited list	No
Weakness	CWE-787
Published	2026-09-03
Last modified	2026-09-10

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

Last updated 2026-09-10 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-03 15:17 UTCPublished CVE record published
2026-09-10 19:50 UTCUpdated Record last modified

mongodb c driver UPGRADE

Affected: >= 1.30.0 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 1.30.0

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 1.30.0 (Debian / Ubuntu)

apt-cache madison c-driver sudo apt install c-driver=<VERSION_BEFORE_1.30.0> 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_1.30.0> 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-2026-84969?

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

Is CVE-2026-84969 being exploited?

CVE-2026-84969 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-2026-84969 affect?

CVE-2026-84969 affects c driver. Severity is low (CVSS 3.7). A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length

How urgent is CVE-2026-84969?

Priority 23/100. Remotely exploitable, no login, no user action

Software pages

MongoDB vulnerabilities

Related CVEs

CVE-2026-6231 MEDIUM 4.3 UPGRADE The bson_validate function may return early on specific inputs and incorrectly report success
CVE-2026-6691 HIGH 7.8 UPGRADE The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username canonicalization,
CVE-2026-81524 MEDIUM 5.4 UPGRADE A weakness in the MongoDB C Driver allows special elements in caller-supplied database and collection name com
CVE-2026-84963 MEDIUM 5.3 UPGRADE An incorrect numeric conversion in the JSON parsing component of the MongoDB C Driver's BSON library may cause
CVE-2026-84964 MEDIUM 5.9 UPGRADE A double free in the OpenSSL-based TLS certificate revocation checking path of the MongoDB C Driver can be rea

References

← Back to latest CVEs