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CVE Record

CVE-2026-9743: Aggregation sub-pipeline null dereference may allow DoS via crafted getMore

In MongoDB Server 8.0, an aggregation stage can leave its _subPipeline field null during processing of certain pipelines. If a getMore is subsequently issued on the same cursor, the server may dereference this null sub-pipeline when reattaching to the operation context, accessing an invalid address and crashing the process. This issue allows an authenticated user who can run aggregation pipelines to cause a denial of service by issuing a specially crafted aggregation followed by getMore on affected versions.

HighCVSS 7.1Not KEV-listed Updated
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Glexia's Take high

Analyst readout for executives and security teams

Plain-English summary

MongoDB Server 8.0.0 can crash when an authenticated user runs certain aggregation work and then continues the cursor. The business impact is service availability: a permitted database user could cause downtime for affected MongoDB processes. The sources do not show active exploitation or a named fixed version.

Executive priority

Treat this as a high-priority availability issue for any production MongoDB Server 8.0.0 system. It does not indicate data compromise, but a low-privileged authenticated user could crash the database process. Prioritize inventory, access review, monitoring, and vendor guidance.

Technical view

The flaw is a CWE-476 null pointer dereference in MongoDB Server 8.0.0. Certain aggregation processing can leave _subPipeline null; a later getMore on the same cursor may dereference it while reattaching operation context, crashing the server process. Exploitation requires network access, low privileges, and ability to run aggregation pipelines.

Likely exposure

Exposure appears limited to MongoDB Server 8.0.0 instances where authenticated users can execute aggregation pipelines. The CVE data lists other versions as unaffected by default, but teams should verify exact build and vendor status before dismissing risk.

Exploitation context

The CVE is not listed as KEV, and the supplied sources do not report active exploitation. The described attack path is authenticated denial of service, not data theft or privilege escalation. Risk rises in shared database environments with broad aggregation permissions.

Researcher notes

Evidence supports an authenticated DoS via null dereference during getMore handling after crafted aggregation cursor state. The source bundle does not provide exploit code, fixed release details, or proof of exploitation. Avoid assuming broader version impact beyond MongoDB Server 8.0.0.

Mitigation direction

  • Identify and prioritize any MongoDB Server 8.0.0 deployments.
  • Check MongoDB SERVER-123688 and CVE records for official fixes or workarounds.
  • Restrict aggregation pipeline privileges to trusted users where feasible.
  • Monitor and alert on unexpected mongod process crashes or restarts.
  • Plan a vendor-supported update when MongoDB identifies a fixed release.

Validation and detection

  • Confirm MongoDB server versions and flag any 8.0.0 instances.
  • Review users and roles allowed to run aggregation pipelines.
  • Check logs for crashes correlated with aggregation cursor activity.
  • Verify high-availability failover and restart behavior for affected services.
  • Recheck vendor references before marking remediation complete.
Prepared
Confidence
medium
Sources
3

Public sources used

Based on public source material and reviewed before publication.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-476: Exact CWE lookup

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cve · low confidence lookup

CVE-2026-9743 mapping review

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Vulnerability profile CVE Program record
Severity
High
CVSS
7.1 (4.0)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2 CVSS vectors
3 Timeline events
1 ADP providers
2 Source links

SSVC decision data

CISA-ADP CISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

Score Version Severity Vector Exploit Impact Source
7.1 CVSS 4.0 High CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N — — mongodb
6.5 CVSS 3.1 Medium CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H 2.8 3.6 mongodb

Vulnerability scoring details

Base CVSS 4.0 score

7.1 High
CVSS 4.0 vector shape for CVE-2026-9743 Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reserved CVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE published CVE Program

    The CVE record was published.

  3. CVE updated CVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADP CISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

Vendor Product Version / package Status
MongoDB MongoDB server 8.0.0 unaffected
Weakness

CWE details

CWE-476

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-476 · source CWE mapping

NULL Pointer Dereference

NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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