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CVE-2026-126982VulnerabilityPublished

Type Allow-list Bypass

Source GCVE Database

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Authoritative record:CVE-2026-126982· High 7.7

Not known to be exploited · CVSS 7.7 High : upgrade to 3.14.0 soon.

Data as of 13 Nov 2026, 01:09 UTC

CVSS 4.0 base score
7.7High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (mongodb)CVSS 4.07.7
CNA (mongodb)CVSS 3.17.5
Patch
Available – fixed in 3.14.0
CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 12 Nov 2026.

What to do

Upgrade C# Driver and mongodb.driver to 3.14.0.

Affected software

ProductAffectedFixed in
MongoDBC# DriverAffected
  • >=3.2.0 <3.14.0
Fixed in
  • 3.14.0
NuGetmongodb.driverpkg:nuget/mongodb.driverOther threatsAffected
  • >=3.2.0 <3.14.0
Fixed in
  • 3.14.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, applications should avoid deserializing polymorphic data into loosely typed members or implement strict input validation and type restrictions to prevent unauthorized type instantiation.

Description

CVE-2026-126982 is a high-severity vulnerability in the BSON serialization library of the MongoDB C# Driver. It allows bypassing a type allow-list restriction during deserialization of polymorphic data into loosely typed members. An attacker who can supply or plant BSON/JSON data that the application deserializes can cause instantiation of unauthorized .NET types with attacker-controlled values. This can lead to arbitrary code execution if a suitable gadget type exists in the application, resulting in loss of confidentiality, integrity, and availability. No special privileges beyond the ability to influence input data are required.

References

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