Quick answers
- Is CVE-2026-93395 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-93395 being exploited in the wild.
- How severe is CVE-2026-93395?
- Medium severity, with a CVSS score of 5.3, published 17 September 2026.
- Which products and versions are affected?
- MongoDB libbson.
- Is there a fix for CVE-2026-93395?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-93395 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-93395?
- Check whether you run MongoDB C Driver or MongoDB Libbson. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is an integer underflow in the bson_new_from_buffer() function caused by missing lower-bound validation on the BSON document length field. The function reads a 32-bit length from the input buffer but does not verify that the value is at least 5 bytes (the minimum valid BSON document size). When the length is zero, an array index calculation wraps to UINT32_MAX, resulting in a heap out-of-bounds read. The attack vector is network-based if BSON input is accepted over the network, and requires no authentication. An attacker can trigger a denial of service by crashing the process with specially crafted BSON data. A patch validating the minimum document length would remediate this issue.
Affected products
- MongoDB libbson
Timeline
- 2026-09-17: disclosed