MongoDB Server: Integer Underflow (Wrap or Wraparound)
CVE-2026-18687 is a high-severity integer underflow (wrap or wraparound) vulnerability in MongoDB Server from MongoDB, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists versions 8.3.8, 8.0.29 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 0.23% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update MongoDB Server to 8.3.8 or 8.0.29, whichever matches your release line, or a later version.
- Update Mongodb to 8.0.29 or 8.3.8, whichever matches your release line, or a later version.
- Read the advisory on jira.mongodb.org for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| MongoDB | MongoDB Server | 8.3.0 up to, but not including, 8.3.8; 8.0 up to, but not including, 8.0.29 | 8.3.8, 8.0.29 |
| MongoDB | Mongodb | 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; 9.1.0 | 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
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- LowLimited modification of data is possible.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H. Scored by CNA (mongodb.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 7.1 | High | CNA (mongodb.com) |
| CVSS 3.1 | 7.1 | High | CNA (mongodb.com) |
Official description
MongoDB Server's handling of a Queryable Encryption maintenance operation did not properly validate certain request parameters against the collection's encrypted field configuration before use. An authenticated user with readWrite privileges could submit a specially formed request that leads to a server crash or excessive internal writes, resulting in resource exhaustion and corruption of encrypted index data.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Integer Underflow (Wrap or Wraparound)
The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
More Integer Underflow (Wrap or Wraparound) vulnerabilities (CWE-191)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in MongoDB Server
- 7.5 High severity
- 8.8 High severity
- 7.1 High severity
- 10.0 Critical severity
- 8.4 High severity
- 7.2 High severity
Recent Integer Underflow (Wrap or Wraparound) vulnerabilities
- 7.8 High severity
- 9.8 Critical severity
- 9.9 Critical severity
- 7.5 High severity
- 7.5 High severity
- 8.1 High severity
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