CVE-2026-9749— Using MaxKey() may crash the server
Quick assessment
Affected
MongoDB MongoDB Server
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
MongoDB Server是美国MongoDB公司的一套开源的NoSQL数据库。该数据库提供面向集合的存储、动态查询、数据复制及自动故障转移等功能。 MongoDB Server存在安全漏洞，该漏洞源于使用内部$exchange阶段配置键范围分区和保序传递时，单个键范围填满交换缓冲区但未更新内部高水位标记，可能导致服务器崩溃或返回错误结果。
Possible ATT&CK Techniques 1 AI
T1499 · Endpoint Denial of ServiceAffected Version Matrix 4
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| MongoDB | MongoDB Server | 8.3.0< 8.3.3 |
affected |
8.2.0< 8.2.10 |
affected | ||
8.0.0< 8.0.24 |
affected | ||
7.0.0< 7.0.35 |
affected |
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I. Basic Information for CVE-2026-9749
Vulnerability Information
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Vulnerability Title
Using MaxKey() may crash the server
Source: CVE Program / CVE List V5
Vulnerability Description
This issue can occur when running an aggregation pipeline that uses the internal $exchange stage configured with key-range partitioning and order-preserving delivery. If a single key range produces enough documents to fill its exchange buffer (that is, many results are routed to the same consumer), the server reaches the code path where a full per-consumer buffer is detected but the internal "high watermark" for that key range is not updated as intended.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
可达断言
Source: CVE Program / CVE List V5
Vulnerability Title
MongoDB Server 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
MongoDB Server是美国MongoDB公司的一套开源的NoSQL数据库。该数据库提供面向集合的存储、动态查询、数据复制及自动故障转移等功能。 MongoDB Server存在安全漏洞，该漏洞源于使用内部$exchange阶段配置键范围分区和保序传递时，单个键范围填满交换缓冲区但未更新内部高水位标记，可能导致服务器崩溃或返回错误结果。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| MongoDB | MongoDB Server | 8.3.0 ~ 8.3.3 | - |
|
II. Public POCs for CVE-2026-9749
| # | POC Description | Source Link | Shenlong Link |
|---|
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Same Patch Batch · MongoDB · 2026-06-09 · 14 CVEs total
| CVE-2026-9753 | 8.1 HIGH | Server crash via malformed binary diff passed to $_internalApplyOplogUpdate. |
| CVE-2026-9740 | 7.5 HIGH | Unbounded recursion in BSONColumn interleaved-reference causes pre-auth stack overflow |
| CVE-2026-9742 | 7.5 HIGH | Authenticate command with specific mechanism parameter can trigger server crash |
| CVE-2026-9750 | 6.5 MEDIUM | Metadata name collision on $-prefixed fields causes post-auth server crash |
| CVE-2026-9748 | 6.5 MEDIUM | $_internalConvertBucketIndexStats may crash the mongod server when working on no timeserie |
| CVE-2026-9747 | 6.5 MEDIUM | Crafted cross-shard merge aggregation crashes MongoDB Server |
| CVE-2026-9741 | 6.5 MEDIUM | Client side encryption fails to encrypt values in a $vectorSearch |
| CVE-2026-9752 | 6.5 MEDIUM | GeometryCollection with strict-winding polygon causes server crash during 2dsphere index k |
| CVE-2026-9746 | 6.5 MEDIUM | Server crashes in case of the use of exchange |
| CVE-2026-9743 | 6.5 MEDIUM | Aggregation sub-pipeline null dereference may allow DoS via crafted getMore |
| CVE-2026-9754 | 6.5 MEDIUM | Stack memory disclosure in filemd5 command |
| CVE-2026-9751 | 5.5 MEDIUM | Sensitive data could be written to mongod.log |
| CVE-2026-9735 | 5.5 MEDIUM | Keyfile contents are in MongoDB Server logs |
IV. Related Vulnerabilities
Same product: MongoDB Server
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CVE-2026-89099
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CVE-2026-82075
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CVE-2026-82074
Incorrect Authorization in MongoDB Server Aggregation Framew -
CVE-2026-82071
Insufficient Validation of Storage Engine Configuration Opti
Same vendor: MongoDB
-
CVE-2026-96749
Heap out-of-bounds write via signed size overflow in BSON do -
CVE-2026-96748
Connection redirection via percent-encoded delimiter injecti -
CVE-2026-96747
Forced local Unix socket connection via dot-sock KMS endpoin -
CVE-2026-96745
PHP object injection via unsuppressible __pclass class infer -
CVE-2026-96746
Heap buffer overflow via mid-scan command list growth in cli
Same weakness: CWE-617
V. Comments for CVE-2026-9749
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