qemu: NULL Pointer Dereference
CVE-2023-3354 is a high-severity NULL pointer dereference vulnerability in qemu, 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. There is no confirmed exploitation so far. EPSS estimates a 1.61% chance of exploitation within 30 days, higher than 76% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of qemu you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| QEMU | qemu | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 6 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 7 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 8 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 8 Advanced Virtualization | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 9 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenStack Platform 13 (Queens) | Not specified in the record | Not stated |
| Fedora | Fedora | Not specified in the record | Not stated |
| Fedora | Extra Packages for Enterprise Linux | Not specified in the record | Not stated |
| Red Hat | Openstack Platform | 13.0 | Not stated |
| Red Hat | Enterprise Linux | 7.0; 8.0; 9.0 | Not stated |
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 NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | CNA (redhat.com) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
A flaw was found in the QEMU built-in VNC server. When a client connects to the VNC server, QEMU checks whether the current number of connections crosses a certain threshold and if so, cleans up the previous connection. If the previous connection happens to be in the handshake phase and fails, QEMU cleans up the connection again, resulting in a NULL pointer dereference issue. This could allow a remote unauthenticated client to cause a denial of service.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: NULL Pointer Dereference
The product dereferences a pointer that it expects to be valid but is NULL.
How developers prevent this class of flaw
- For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
- Select a programming language that is not susceptible to these issues.
- Check the results of all functions that return a value and verify that the value is non-null before acting upon it.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- bugzilla.redhat.com/show_bug.cgi?id=2216478Issue Tracking
Third-party and government advisories
- access.redhat.com/security/cve/CVE-2023-3354Third Party Advisory
Other references
Other vulnerabilities in qemu
- 7.8 High severity
- 8.8 High severity
- 7.1 High severity
- 7.0 High severity
- 8.2 High severity
- 10.0 Critical severity
Recent NULL Pointer Dereference vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 8.8 High severity
- 7.7 High severity
- 7.5 High severity
- 7.5 High severity
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