Analyst readout for executives and security teams
Plain-English summary
CVE-2026-9740 lets an unauthenticated network user crash a MongoDB Server process by sending a malformed message. The known impact is availability loss, not data theft or modification, but a database crash can still disrupt dependent applications.
Executive priority
Treat this as a high-priority availability risk for MongoDB-backed services. Prioritize internet-facing or broadly reachable deployments first, then internal shared database environments. Business urgency depends on whether affected versions are exposed to untrusted traffic.
Technical view
MongoDB Server BSON validation has uncontrolled mutual recursion when processing certain BSONColumn nested binary structures. Re-entry resets internal depth tracking, allowing stack exhaustion and a mongod crash before authentication. The CVSS 4.0 score is 8.7 with high availability impact.
Likely exposure
Exposure is most likely where affected MongoDB Server versions are reachable from untrusted networks. The bundle lists MongoDB Server 8.3.0, 8.2.0, 8.0.0, and 7.0.0 as affected, with other versions defaulting to unaffected.
Exploitation context
The source bundle supports unauthenticated remote denial of service. It does not show CISA KEV listing, active exploitation, public exploit availability, fixed versions, or confirmed mitigations beyond vendor tracking.
Researcher notes
Evidence is limited to the CVE description and MongoDB Jira reference in the provided bundle. The described flaw is CWE-674 uncontrolled recursion in BSON validation, causing pre-auth stack overflow and mongod termination. No confidentiality or integrity impact is claimed.
Mitigation direction
- Check MongoDB SERVER-125063 and vendor advisories for fixed versions or workaround guidance.
- Inventory MongoDB Server versions and prioritize listed affected instances.
- Restrict MongoDB network exposure to trusted application hosts only.
- Ensure service supervision and high availability are configured for mongod restarts.
- Monitor logs and availability alerts for unexpected mongod crashes.
Validation and detection
- Confirm whether any deployed MongoDB Server matches the listed affected version entries.
- Review firewall, security group, and bindIp exposure for each MongoDB instance.
- Check database uptime and crash telemetry since June 9, 2026.
- Verify vendor guidance before applying patches or operational workarounds.
- Document any externally reachable affected instance as high priority.
Public sources used
Based on public source material and reviewed before publication.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-674: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-9740 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.7 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
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.
SSVC decision data
CVSS vector scores
2 official scoresWe 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.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N — — mongodb CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H 3.9 3.6 mongodb Vulnerability scoring details
Base CVSS 4.0 score
8.7 HighVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Base CVSS 3.1 score
7.5 HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reserved CVE Program
The CVE ID was reserved by the assigning CNA.
- CVE published CVE Program
The CVE record was published.
- CVE updated CVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 source CVE List V5
- https://jira.mongodb.org/browse/SERVER-125063 CVE reference, mongodb
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Uncontrolled Recursion
Uncontrolled Recursion represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.