CVE-2026-81523: A missing input-validation issue in MongoDB libmongocrypt's automatic-encryption context setup allows a caller

Q: How do I fix CVE-2026-81523?

libmongocrypt: upgrade to 1.20.3. Exact commands for each OS are on this page.

Q: Is CVE-2026-81523 being exploited?

CVE-2026-81523 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-81523 affect?

CVE-2026-81523 affects libmongocrypt. Severity is medium (CVSS 4.4). A missing input-validation issue in MongoDB libmongocrypt's automatic-encryption context setup allows a caller-supplied database identifier to be accepted without sanitization. The resulting impact is limited to incorrect schema selection,

Q: How urgent is CVE-2026-81523?

Priority 16/100. No elevated risk signals yet.

Routine

MEDIUM 4.4UPGRADE

CVE-2026-81523 is a medium-severity flaw (CVSS 4.4) affecting libmongocrypt. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A missing input-validation issue in MongoDB libmongocrypt's automatic-encryption context setup allows a caller-supplied database identifier to be accepted without sanitization. The resulting impact is limited to incorrect schema selection, which may lead to limited disclosure or modification of information handled by the application.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	4.4 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.1% (top 99%)
CISA exploited list	No
Weakness	CWE-74
Published	2026-08-27
Last modified	2026-09-17

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

Last updated 2026-09-17 · 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
2026-09-17 13:59 UTCUpdated Record last modified

mongodb libmongocrypt UPGRADE

Affected: < 1.20.3

Fixed in: 1.20.3

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy libmongocrypt || rpm -q libmongocrypt || libmongocrypt --version

2. UPGRADE to 1.20.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade libmongocrypt

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libmongocrypt

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2026-81523?

libmongocrypt: upgrade to 1.20.3. Exact commands for each OS are on this page.

Is CVE-2026-81523 being exploited?

CVE-2026-81523 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-2026-81523 affect?

CVE-2026-81523 affects libmongocrypt. Severity is medium (CVSS 4.4). A missing input-validation issue in MongoDB libmongocrypt's automatic-encryption context setup allows a caller-supplied database identifier to be accepted without sanitization. The resulting impact is limited to incorrect schema selection,

How urgent is CVE-2026-81523?

Priority 16/100. No elevated risk signals yet.

Software pages

MongoDB vulnerabilities

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References

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