What’s Vulnerable › Vulnerabilities

CVE-2026-106433: Heap corruption via duplicate masterKey fields in MongoDB libmongocrypt

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-08 · updated 2026-10-27
• Weakness: CWE-843

Description

Improper state management in MongoDB libmongocrypt can cause provider-specific data to be treated as an incompatible type when cleaning up a key document containing duplicate masterKey fields. An authenticated actor who can modify key vault documents, or a server that returns such a key document, can cause invalid memory access and invalid frees in the client process. This can terminate the application or corrupt process memory.

Affected products

• MongoDB libmongocrypt: from 1.5.0 before 1.20.5 — fixed in 1.20.5
• MongoDB libmongocrypt: from 1.1.0 before 1.20.5 — fixed in 1.20.5

How to fix

Upgrade to a fixed version: MongoDB libmongocrypt 1.20.5; MongoDB libmongocrypt 1.20.5. Check the vendor advisory for mitigations.

References

• https://jira.mongodb.org/browse/MONGOCRYPT-964

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