Denial of service in MongoDB libmongocrypt via malformed KMS endpoint
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-191 and the CVSS impact.
Summary
MongoDB libmongocrypt from 1.1.0 before 1.20.5 has an integer underflow (CWE-191) in KMS endpoint parsing. The underflow causes an allocation failure that terminates the application process. An authenticated user who modifies a key document in the key vault collection can trigger it, as can an application that accepts a KMS endpoint with a colon after its path or query during key creation.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Description from the CNA
An integer underflow in the KMS endpoint-parsing logic of MongoDB libmongocrypt can cause an allocation failure that terminates the application process. This can occur when an authenticated user modifies a key document in the key vault collection, or when an application accepts a KMS endpoint containing a colon after its path or query during key creation. The issue does not access memory outside its allocated bounds.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
Upgrade MongoDB libmongocrypt to version 1.20.5.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
- Fix · CNA libmongocrypt (MongoDB) Fixed in 1.20.5
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
MongoDB libmongocrypt 1.20.5
3 records Highest priority Priority LOW 3 LOW
Other records, highest priority first
- TI-2026-69711 Memory corruption in MongoDB libmongocrypt with duplicate masterKeyPriority LOW 39
- TI-2026-69712 Unrecognized payload accepted as plaintext in libmongocrypt decryptionPriority LOW 23
Vendor assessments
Timeline
- 2026-10-09 Threatist record created from CVE-2026-106429
- 2026-10-10 Affected versions changed · Red Hat
- 2026-10-10 CVSS score added · Red Hat
References
More MongoDB vulnerabilities
- TI-2019-08023 Code injection in mongo-express KEVCVSS 3.1CRITICAL 9.9
- TI-2025-13542 Zlib compressed protocol header length confusion may allow memory read KEVCVSS 4.0HIGH 8.7
- TI-2026-79432 BSON output corruption via out-of-range binary subtype in MongoDB C# Driver CVSS 4.0MEDIUM 6.9
- TI-2026-79424 NoSQL command injection via mismatched BSON length in MongoDB C# Driver CVSS 4.0MEDIUM 6.9
- TI-2026-79422 Unbounded memory growth in MongoDB C# Driver BSON deserialization CVSS 4.0HIGH 8.2
- TI-2026-79427 Authentication bypass via issuer-and-serial-only certificate equality CVSS 4.0HIGH 7.6
Sources
- CVE-2026-106429 · CVE Program
- CVE-2026-106429 · NVD
- FIRST EPSS
- CVE-2026-106429 · Red Hat security data · CC BY 4.0
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