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CVE-2026-106431— One-byte heap buffer overflow in BSON bulk document writer in MongoDB C Driver

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 驱动程序中的 BSON 批量文档写入器存在一个“差一错误”（off-by-one error）。当某个文档恰好结束于特定的缓冲区边界时，该漏洞会在堆分配内存之后的一个字节处写入一个额外的零字节。攻击者若能影响由嵌入应用程序序列化的文档大小，即可导致相邻进程内存被破坏或使进程崩溃。要触发此漏洞，应用程序必须使用 BSON 批量写入器 API，并生成精确的累计文档大小。

CVSS 5.7 · Medium

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 2

VendorProduct Version RangeStatus
MongoDB C Driver 0.5.0< 1.30.13 affected
2.0.0< 2.5.6 affected
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I. Basic Information for CVE-2026-106431

Vulnerability Information
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Vulnerability Title
One-byte heap buffer overflow in BSON bulk document writer in MongoDB C Driver
Source: CVE Program / CVE List V5
Vulnerability Description
An off-by-one error in the BSON bulk document writer in the MongoDB C Driver can write one zero byte immediately past a heap allocation when a document ends at a specific buffer boundary. An actor who can influence the size of documents serialized by an embedding application can corrupt adjacent process memory or terminate the process. Reaching this issue requires the application to use the BSON bulk-writer API and produce a precise cumulative document size.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存写
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
MongoDB C Driver 0.5.0 ~ 1.30.13 -

II. Public POCs for CVE-2026-106431

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III. Intelligence Information for CVE-2026-106431

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Other References for CVE-2026-106431 (1)

Same Patch Batch · MongoDB · 2026-10-08 · 13 CVEs total

CVE-2026-106433 8.8 HIGH Heap corruption via duplicate masterKey fields in MongoDB libmongocrypt
CVE-2026-106429 6.5 MEDIUM Application denial of service via malformed KMS endpoint in MongoDB libmongocrypt
CVE-2026-106437 6.2 MEDIUM Out-of-bounds read and write via undersized BSON buffer reservation in MongoDB C Driver
CVE-2026-106430 5.9 MEDIUM Query and rename target confusion via embedded NUL truncation in MongoDB C++ Driver
CVE-2026-107325 5.9 MEDIUM Application denial of service via missing BSON array length validation in MongoDB Go Drive
CVE-2026-107324 5.9 MEDIUM Application denial of service via integer overflow in BSON value-length validation in Mong
CVE-2026-106435 5.1 MEDIUM Application denial of service via out-of-bounds read in BSON Regex decoding in MongoDB Pyt
CVE-2026-106436 4.8 MEDIUM Application denial of service and data truncation via unchecked BSON append failures in Mo
CVE-2026-106434 4.3 MEDIUM Unrecognized payload acceptance in explicit decryption in MongoDB libmongocrypt
CVE-2026-106438 4.0 MEDIUM Silent Decimal128 value corruption via incorrect exactness check in MongoDB C Driver
CVE-2026-106428 3.7 LOW Out-of-bounds read in SCRAM response parsing in MongoDB C Driver
CVE-2026-106432 3.6 LOW Heap buffer overflow via 32-bit string-length truncation in MongoDB PHP Driver

IV. Related Vulnerabilities

Same product: C Driver
Same vendor: MongoDB
Same weakness: CWE-787

V. Comments for CVE-2026-106431

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