CVE-2026-81523 Cross-tenant database retargeting via dot/NUL injection in namespace strings in libmongocrypt

Low 2.0 Published 27 Aug 2026 Updated 28 Aug 2026

Attackers can manipulate database identifiers to cause incorrect schema selection, leading to limited data disclosure or modification in applications using libmongocrypt.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2026-81523?

CVE-2026-81523 is a low-severity vulnerability in MongoDB libmongocrypt, published on 27 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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.

Weakness: CWE-74

Which versions are affected by CVE-2026-81523?

It affects 1 product.

Products include Mongodb Libmongocrypt.

How do I fix CVE-2026-81523?

Apply the vendor's patch.

Is CVE-2026-81523 being exploited?

There is no known exploitation of CVE-2026-81523 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2026-81523, UBUNTU-CVE-2026-81523.