CVE-2026-84970— Heap over-read or silent misparse via 32-bit truncation of JSON length in BSON JSON parser
Quick assessment
Affected
MongoDB C++ Driver
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 C++ Driver是美国MongoDB公司的一个C++驱动。 MongoDB C++ Driver 3.2.0版本至4.5.2之前版本存在数字错误漏洞，该漏洞源于其BSON库的JSON解析组件存在数值截断问题。当攻击者控制嵌入应用程序传递给该库公共JSON解析接口的超大文本时，可能导致库越界读取内存并将数据返回给调用者、仅将部分输入静默作为完整文档接受，或终止进程。该漏洞无需MongoDB服务器、凭据或非默认配置，影响仅限使用该库的进程。
Possible ATT&CK Techniques 1 AI
T1190 · Exploit Public-Facing ApplicationAffected Version Matrix 1
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| MongoDB | C++ Driver | 3.2.0< 4.5.2 |
affected |
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I. Basic Information for CVE-2026-84970
Vulnerability Information
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Vulnerability Title
Heap over-read or silent misparse via 32-bit truncation of JSON length in BSON JSON parser
Source: CVE Program / CVE List V5
Vulnerability Description
A numeric truncation weakness exists in the JSON parsing component of the MongoDB C++ Driver's BSON library. An actor who controls the text that an embedding application hands to the library's public JSON parsing interface, when that text is very large, can cause the library to read memory beyond the supplied buffer and return it to the caller, to silently accept only part of the input as a complete document, or to terminate the process. No MongoDB server, credentials, or non-default configuration is required; the effect is confined to the process that uses the library.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
数值类型间的不正确转换
Source: CVE Program / CVE List V5
Vulnerability Title
MongoDB C++ Driver 数字错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
MongoDB C++ Driver是美国MongoDB公司的一个C++驱动。 MongoDB C++ Driver 3.2.0版本至4.5.2之前版本存在数字错误漏洞，该漏洞源于其BSON库的JSON解析组件存在数值截断问题。当攻击者控制嵌入应用程序传递给该库公共JSON解析接口的超大文本时，可能导致库越界读取内存并将数据返回给调用者、仅将部分输入静默作为完整文档接受，或终止进程。该漏洞无需MongoDB服务器、凭据或非默认配置，影响仅限使用该库的进程。
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 | C++ Driver | 3.2.0 ~ 4.5.2 | - |
|
II. Public POCs for CVE-2026-84970
| # | POC Description | Source Link | Shenlong Link |
|---|
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Other References for CVE-2026-84970 (1)
Same Patch Batch · MongoDB · 2026-09-03 · 10 CVEs total
| CVE-2026-84971 | 6.5 MEDIUM | Persistent client crash loop via undersized FLE2 insert-update ciphertext in decryption pa |
| CVE-2026-84964 | 5.9 MEDIUM | Heap corruption via OCSP request double free from crafted multi-URL certificate in TLS cli |
| CVE-2026-84963 | 5.3 MEDIUM | Silent field truncation via unchecked int cast of huge JSON string values in JSON-to-BSON |
| CVE-2026-84968 | 5.3 MEDIUM | Heap out-of-bounds read via corrupt nested BSON in field path error message |
| CVE-2026-84965 | 5.1 MEDIUM | Heap write primitive via size round-up wrap during JSON parsing on 32-bit builds |
| CVE-2026-84966 | 5.1 MEDIUM | BSON element injection via NUL-embedded document keys in builder append |
| CVE-2026-84967 | 4.3 MEDIUM | Arbitrary command execution via shell-expanded connection string in Launch MongoDB Shell t |
| CVE-2026-84962 | 4.2 MEDIUM | Authenticated KMS request forgery via CRLF injection in GCP key identifier strings |
| CVE-2026-84969 | 3.7 LOW | Heap overflow via truncated base64 encoding of binary fields in length-limited JSON output |
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