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NVD / CVE Program· CNA mongodb

CVE-2026-81528: NoSQL injection via array replacement bypassing update shape validation in driver write path

Noroxi assessment

Priority: Monitor (action score 21/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.27% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: MongoDB C# Driver 3.11.1.

Low priority for now. Upgrade to MongoDB C# Driver 3.11.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

A MongoDB C# driver document-replacement code path omits the element-name/shape validation that the equivalent write paths apply, so a value supplied as a replacement is forwarded to the server without neutralization of query-language special elements. An application that passes untrusted, loosely-typed input as a replacement value therefore allows that input to be interpreted by the database as update logic rather than as data, executing under the application's own database credentials. Applications using strongly-typed document mappings are not affected.

MediumCVSS 5.3 · v4.0—No exploit Fix available
Published
Aug 27, 2026
Updated
Sep 29, 2026
EPSS
0.2% · 20th percentile

Report tools

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Action score

21

Monitor

Low priority for now.

CVSS
21 / 40 · 5.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · mongodb
5.3
NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
mongodbc# driver

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • mongodb c# driver2.10.0 and later · before 3.11.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (mongodb). Independent of NVD's CPE analysis and usually ahead of it.

  • MongoDB C# Driver

    • 2.9.0 and later · before 3.11.1affected · semver

Same product

mongodb: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-114644Memory-exhaustion denial of service via unbounded symbol interning during BSON/JSON deserialization
    32Monitor
  • CVE-2026-114649Authentication bypass via issuer-and-serial-only certificate equality in shared cluster cache
    30Monitor
  • CVE-2026-114653Silent client-side encryption bypass via unescaped field-name regex in CSFLE schema builder
    28Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-81527Aug 27, 2026 · NoSQL injection via unquoted constant GroupBy keys in LINQ pipeline translation
    27Monitor
  • Later →CVE-2026-81529Aug 27, 2026 · Connection-option injection via unescaped settings in the canonical MongoDB URL builder
    28Monitor
  • Later →CVE-2026-81530Aug 27, 2026 · KMS master key exposure via unredacted credential serialization in driver settings string
    27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
MongoDB C# Driver3.11.1Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-8802614 days apartRegular expression injection via unescaped characters in LINQ query translation in MongoDB C# Driver
    28Monitor
  • CVE-2026-11464856 days apartNoSQL injection via dot and dollar characters in LINQ filter field names and dictionary keys
    28Monitor
  • CVE-2026-11465256 days apartUpdate operator injection via single-element list rewriting in the update builder
    28Monitor
  • CVE-2026-815270 days apartNoSQL injection via unquoted constant GroupBy keys in LINQ pipeline translation
    27Monitor
  • CVE-2026-8802514 days apartGridFS data disclosure and deletion via query-operator injection in file IDs in the MongoDB C# Driver
    24Monitor
  • CVE-2026-11464756 days apartNoSQL operator injection via unvalidated replacement document in findOneAndReplace
    21Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
X

Weakness class (CWE)

CWE-943 · Improper Neutralization of Special Elements in Data Query Logic

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

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References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records