CVE-2026-18687Network attack vectorHinoki check available

Authenticated crash and index corruption via range underflow

Published Aug 11, 2026 · Updated Aug 11, 2026

Integer underflow in MongoDB Server 8.0 before 8.0.29 and 8.3.0 through 8.3.7 allows remote authenticated users to crash the server. The FLE2 compaction path fails to validate maintenance parameters against encrypted-field configuration before calculating range padding, causing an integer underflow and excessive ESC insertions. A user with readWrite privileges can issue the crafted maintenance request, exhausting resources, crashing the process, or corrupting encrypted index data.

CVSS severity7.1
High
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Integer underflow in MongoDB Server 8.0 before 8.0.29 and 8.3.0 through 8.3.7 allows remote authenticated users to crash the server. The FLE2 compaction path fails to validate maintenance parameters against encrypted-field configuration before calculating range padding, causing an integer underflow and excessive ESC insertions. A user with readWrite privileges can issue the crafted maintenance request, exhausting resources, crashing the process, or corrupting encrypted index data.

The record

CVE
CVE-2026-18687
Published
Aug 11, 2026
Updated
Aug 11, 2026
Vendor
MongoDB
Product
MongoDB Server
Classifications
CWE-191, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=8.0 <8.0.29
  2. Affected versionversion=8.3.0 <8.3.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

MongoDB · MongoDB Serverversion=8.0 <8.0.29; version=8.3.0 <8.3.8

Published CVSS scores

7.1MongoDBCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
7.1MongoDBCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-191Integer Underflow (Wrap or Wraparound)
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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