Is there a public exploit for CVE-2026-126839?

No public exploit for CVE-2026-126839 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

How severe is CVE-2026-126839?

CVE-2026-126839 scores CVSS 2.3 (v4.0), rated low.

What does CVE-2026-126839 affect?

CVE-2026-126839 affects MONGODB C# Driver.

2.3 Low

A deserialization type-restriction control in the BSON serialization component can be bypassed because the check used to recognize a class…

CVE-2026-126839

A deserialization type-restriction control in the BSON serialization component can be bypassed because the check used to recognize a class of compiler-generated types relies on an overly permissive heuristic rather than a precise identification. An unauthorized party able to supply BSON content that an application later deserializes into a loosely typed member can cause types outside the intended allow-list to be constructed and populated with unauthorized party-supplied values inside the consuming application. This can lead to unexpected object state and errors in downstream application logic. No elevated privileges beyond the ability to place unauthorized party-influenced content in the deserialization path are required.

Assessment

CVSS: 2.3 (v4.0)
Severity: Low
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 13 November 2026
Last updated: 13 November 2026
Affected: MONGODB · C# Driver
Assigner: mongodb

CVSS vectorCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

At the source

EUVD (ENISA)

References

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