Vulnerability · Published Sep 3, 2026 · Assigned by mongodb
CVE-2026-84965Heap write primitive via size round-up wrap during JSON parsing on 32-bit builds
Medium 5.1
In plain English
A medium-severity integer overflow 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 2% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
An integer wraparound in an allocation size calculation in the BSON library's JSON parsing code can cause a buffer to be released while a following copy operation still writes through the stale pointer. On builds where sizes are 32 bits, an unauthenticated party able to supply a sufficiently large JSON input to an application that links the library may cause that application to terminate unexpectedly, resulting in denial of service.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.24 | mongo-c-driver | 1.30.14-r0 | ALPINE-CVE-2026-84965 |
| Debian:12 | mongo-c-driver | no fix listed | DEBIAN-CVE-2026-84965 |
| Debian:13 | mongo-c-driver | no fix listed | DEBIAN-CVE-2026-84965 |
| Debian:14 | mongo-c-driver | 2.5.2-1 | DEBIAN-CVE-2026-84965 |
| Ubuntu:26.04:LTS | mongo-c-driver | no fix listed | UBUNTU-CVE-2026-84965 |
| Ubuntu:26.10 | mongo-c-driver | no fix listed | UBUNTU-CVE-2026-84965 |
Affected products (as reported)
Weakness: CWE-190 · Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H