Vulnerability · Published Oct 8, 2026 · Assigned by mongodb
CVE-2026-106438Silent Decimal128 value corruption via incorrect exactness check in MongoDB C Driver
Medium 4.0
In plain English
A medium-severity security flaw in C Driver from MongoDB. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
An incorrect calculation in Decimal128 string parsing in the MongoDB C Driver can accept certain over-precision inputs containing leading zeros instead of rejecting them. This produces a value different from the supplied text. An actor who can provide a decimal string to an embedding application, including through Extended JSON parsing, can cause the application to store or use an incorrect numeric value.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | mongo-c-driver | no fix listed | DEBIAN-CVE-2026-106438 |
| Debian:13 | mongo-c-driver | no fix listed | DEBIAN-CVE-2026-106438 |
| Debian:14 | mongo-c-driver | 2.5.6-1 | DEBIAN-CVE-2026-106438 |
| Ubuntu:26.04:LTS | mongo-c-driver | no fix listed | UBUNTU-CVE-2026-106438 |
| Ubuntu:26.10 | mongo-c-driver | no fix listed | UBUNTU-CVE-2026-106438 |
Affected products (as reported)
Weakness: CWE-682 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N