Kernel: Double Free
CVE-2023-4389 is a high-severity double free vulnerability in Kernel, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. There is no confirmed exploitation so far. EPSS estimates a 0.25% 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 Linux Kernel to 5.10.112 or 5.15.35 or 5.17.4, whichever matches your release line, or a later version.
- Read the advisory on patchwork.kernel.org for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Kernel | Kernel | 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 9 | Not specified in the record | Not stated |
| Fedora | Fedora | Not specified in the record | Not stated |
| Linux | Linux Kernel | 5.7 up to, but not including, 5.10.112; 5.11 up to, but not including, 5.15.35; 5.16 up to, but not including, 5.17.4 | 5.10.112, 5.15.35, 5.17.4 |
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
- LocalThe attacker needs local access or must trick a user into running something.
- 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
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.0 | High | CNA (redhat.com) |
| CVSS 3.1 | 7.1 | High | NVD |
Official description
A flaw was found in btrfs_get_root_ref in fs/btrfs/disk-io.c in the btrfs filesystem in the Linux Kernel due to a double decrement of the reference count. This issue may allow a local attacker with user privilege to crash the system or may lead to leaked internal kernel information.
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: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- access.redhat.com/security/cve/CVE-2023-4389Third Party Advisory
- bugzilla.redhat.com/show_bug.cgi?id=2219271Issue Tracking, Third Party Advisory
Other vulnerabilities in Kernel
- 7.5 High severity
- 7.8 High severity
- 8.1 High severity
- 8.1 High severity
- 8.1 High severity
- 7.5 High severity
Recent Double Free vulnerabilities
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
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