MongoDB Libmongocrypt Driver up to 1.21.2 Key-Management Request-Building out-of-bounds write

Summaryinfo

A vulnerability categorized as problematic has been discovered in MongoDB Libmongocrypt Driver up to 1.21.2. Impacted is an unknown function of the component Key-Management Request-Building. The manipulation results in out-of-bounds write. This vulnerability is cataloged as CVE-2026-126792. The attack must be initiated from a local position. There is no exploit available.

Detailsinfo

A vulnerability, which was classified as problematic, was found in MongoDB Libmongocrypt Driver up to 1.21.2. Affected is an unknown functionality of the component Key-Management Request-Building. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. CWE is classifying the issue as CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. This is going to have an impact on integrity, and availability. CVE summarizes:

A memory-safety flaw in the key-management request-building component of the library can lead to an out-of-bounds write on the heap. A fixed-size output buffer is used under an assumption about cryptographic key size that is never validated, so when the library is embedded by a caller that supplies its own cryptographic callback implementation, data larger than the buffer can be written past its end. Exploitation requires the ability to control the embedding application's in-process key-management provider configuration, a high-privilege position. The demonstrated impact is memory corruption resulting in abnormal termination of the client process.

The advisory is shared for download at jira.mongodb.org. This vulnerability is traded as CVE-2026-126792 since 11/11/2026. The exploitability is told to be easy. The attack needs to be approached locally. Additional levels of successful authentication are needed for exploitation. There are neither technical details nor an exploit publicly available.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Database Software

Vendor

• MongoDB

Name

• Libmongocrypt Driver

Version

• 1.21.0
• 1.21.1
• 1.21.2

License

• open-source

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CPE 2.2info

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