CyberSecBulletin
CVE-2026-18697NVD status: Analyzed

MongoDB Server: Reachable Assertion

Published Updated By the CyberSecBulletin desk

CVE-2026-18697 is a high-severity reachable assertion vulnerability in MongoDB Server from MongoDB, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 8.3.8, 8.0.29, 7.0.40 as the first without the flaw, so updating MongoDB Server to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.44% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update MongoDB Server to 8.3.8 or 8.0.29 or 7.0.40, whichever matches your release line, or a later version.
  2. Update Mongodb to 7.0.40 or 8.0.29 or 8.3.8, whichever matches your release line, or a later version.
  3. Read the advisory on jira.mongodb.org for workarounds and exact fixed builds.
  4. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
MongoDBMongoDB Server8.3.0 up to, but not including, 8.3.8; 8.0 up to, but not including, 8.0.29; 7.0 up to, but not including, 7.0.408.3.8, 8.0.29, 7.0.40
MongoDBMongodb7.0.0 up to, but not including, 7.0.40; 8.0.0 up to, but not including, 8.0.29; 8.2.0 through 8.2.12; 8.3.0 up to, but not including, 8.3.8; 9.0.0; 9.1.07.0.40, 8.0.29, 8.3.8

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA (mongodb.com).

Scoring systemScoreSeverityScored by
CVSS 4.08.7HighCNA (mongodb.com)
CVSS 3.17.5HighCNA (mongodb.com)

Official description

An issue in MongoDB Server's aggregation framework could allow an unauthenticated party to cause a mongos (router) process to terminate unexpectedly by submitting a specially formed aggregation command. This could result in a denial of service, disrupting client connections routed through the affected mongos instance.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Reachable Assertion

The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.

How developers prevent this class of flaw

  • If the assertion statement is required (e.g., for security or reliability), change the invoking code to avoid the conditions that trigger the assertion.
  • Consider changing the assertion to some other less fatal error. This might not be easy to implement, since other code may be needed to handle the error.
  • Make sensitive open/close operations non-reachable from directly user-controlled data (e.g. open/close resources)

More Reachable Assertion vulnerabilities (CWE-617)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in MongoDB Server

All MongoDB Server vulnerabilities

Recent Reachable Assertion vulnerabilities

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