MongoDB Server: Double Free
CVE-2026-4358 is a high-severity double free 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 attacker with a low-privileged account, without any action from a user. The record lists versions 8.2.6, 8.0.20, 7.0.31 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 0.39% 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 8.2.6 or 8.0.20 or 7.0.31, whichever matches your release line, or a later version.
- Update Mongodb to 7.0.31 or 8.0.20 or 8.2.6, 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 | 8.2 up to, but not including, 8.2.6; 8.0 up to, but not including, 8.0.20; 7.0 up to, but not including, 7.0.31 | 8.2.6, 8.0.20, 7.0.31 |
| MongoDB | Mongodb | 7.0.0 up to, but not including, 7.0.31; 8.0.0 up to, but not including, 8.0.20; 8.2.0 up to, but not including, 8.2.6 | 7.0.31, 8.0.20, 8.2.6 |
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
- HighSuccess depends on conditions outside the attacker's control.
- 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
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 6.1 | Medium | CNA (mongodb.com) |
| CVSS 3.1 | 6.4 | Medium | CNA (mongodb.com) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
A specially crafted aggregation query with $lookup by an authenticated user with write privileges can cause a double-free or use-after-free memory issue in the slot-based execution (SBE) engine when an in-memory hash table is spilled to disk.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Double Free
The product calls free() twice on the same memory address.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
- Use a static analysis tool to find double free instances.
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 Double Free vulnerabilities
- 7.0 High severity
- 7.5 High severity
- 7.8 High severity
- 7.8 High severity
- 7.5 High severity
- 7.8 High severity
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