CVE-2026-88035: A size check in the client-side authentication path of the MongoDB C Driver can wrap around, so an unusually l

Routine

MEDIUM 4.7UPGRADE

CVE-2026-88035 is a medium-severity flaw (CVSS 4.7) affecting c driver. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A size check in the client-side authentication path of the MongoDB C Driver can wrap around, so an unusually large user-name value is accepted and copied past the end of a small buffer. A party able to set the driver's connection settings may cause the application that embeds the driver to terminate unexpectedly. Reaching this code requires a build in which the optional external SASL authentication backend is present and a connection configured t

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	4.7 (Medium)
Attack vector	Local
Attack complexity	High
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.1% (top 99%)
CISA exploited list	No
Weakness	CWE-190
Published	2026-09-10
Last modified	2026-09-16

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

Last updated 2026-09-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-10 19:17 UTCPublished CVE record published
2026-09-16 18:08 UTCUpdated Record last modified

mongodb c driver UPGRADE

Affected: >= 1.10.0 and < 1.30.10 · >= 2.2.0 and < 2.5.3

Fixed in: 1.30.10, 2.5.3

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 1.30.10 (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-2026-88035?

c driver: upgrade to 1.30.10, 2.5.3. Exact commands for each OS are on this page.

Is CVE-2026-88035 being exploited?

CVE-2026-88035 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-2026-88035 affect?

CVE-2026-88035 affects c driver. Severity is medium (CVSS 4.7). A size check in the client-side authentication path of the MongoDB C Driver can wrap around, so an unusually large user-name value is accepted and copied past the end of a small buffer. A party able to set the driver's connection settings m

How urgent is CVE-2026-88035?

Priority 17/100. No elevated risk signals yet.

Software pages

MongoDB vulnerabilities

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References

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