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Fencer Intel
medium 4.0

CVE-2026-114651 json

Cross-document data leak via malformed BSON array parsing in reused thread buffer

published 18d ago modified 10d ago also EUVD-2026-108322

cvss
4.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 33%
public exploits
0
none known

Summary

A memory-handling weakness in the BSON deserialization component of the MongoDB C# Driver may cause data left over from previously processed content to be returned when specially crafted serialized input is parsed. An unauthenticated party able to supply serialized data to an application that maps certain primitive collection types can cause residual bytes from unrelated data processed earlier on the same execution thread to be surfaced as legitimate values. This can result in disclosure of a limited amount of information belonging to other requests or principals of the consuming application. No authentication or special privileges within the application are required.

Patch / fix

  • MongoDB C# Driver 3.13.0

Is CVE-2026-114651 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
10d ago

Exploit prediction

0.39% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/mongodb/mongo-csharp-driver/security/advisories/GHSA-f8xm-c88f-wq46 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N
CNA 3.1 4.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • MongoDB C# Driver

Classification

Weakness
  • CWE-908 Use of Uninitialized Resource

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.