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VulnerabilityPublished

CVE-2026-120954: MongoDB C Driver · Integer Overflow or Wraparound

Affects MongoDB C DriverSource CVE Database V5

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Not known to be exploited · CVSS 6.3 Medium.

Data as of 3 Nov 2026, 19:58 UTC

CVSS 4.0 base score
6.3Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (mongodb)CVSS 4.06.3
CNA (mongodb)CVSS 3.13.7
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
MongoDBC DriverAffected
  • >=2.0.0 <=2.5.7
Fixed in–

AI-suggested

Until a fix is available, avoid parsing untrusted BSON data on 32-bit builds of the MongoDB C Driver or implement application-level validation to detect and reject oversized element counts in BSON binary vector types.

Description

A weakness in the BSON library's handling of a specialized binary vector data type allows an arithmetic wraparound when computing the number of elements described by an oversized attacker-supplied value. On builds where the platform word size is 32 bits, an application that parses untrusted BSON data can be made to process only a small fraction of the supplied elements while the operation reports success, producing results that disagree with byte-oriented accessors and with 64-bit builds of the same library. No authentication or user interaction is required beyond getting the application to parse the data. The impact is limited to data integrity; memory safety is not affected and no information is disclosed.

References

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