Linux: Use After Free
CVE-2023-52846 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 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. The record lists versions ddf4e04e946aaa6c458b8b6829617cc44af2bffd, a1a485e45d24b1cd8fe834fd6f1b06e2903827da, 6086258bd5ea7b5c706ff62da42b8e271b2401db as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.34% 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 to ddf4e04e946aaa6c458b8b6829617cc44af2bffd or a1a485e45d24b1cd8fe834fd6f1b06e2903827da or 6086258bd5ea7b5c706ff62da42b8e271b2401db or 1787b9f0729d318d67cf7c5a95f0c3dba9a7cc18, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.201 or 5.15.139 or 6.1.63 or 6.5.12, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 451d8123f89791bb628277c0bdb4cae34a3563e6 up to, but not including, ddf4e04e946aaa6c458b8b6829617cc44af2bffd; 451d8123f89791bb628277c0bdb4cae34a3563e6 up to, but not including, a1a485e45d24b1cd8fe834fd6f1b06e2903827da; 451d8123f89791bb628277c0bdb4cae34a3563e6 up to, but not including, 6086258bd5ea7b5c706ff62da42b8e271b2401db; 451d8123f89791bb628277c0bdb4cae34a3563e6 up to, but not including, 1787b9f0729d318d67cf7c5a95f0c3dba9a7cc18; 451d8123f89791bb628277c0bdb4cae34a3563e6 up to, but not including, d103fb6726904e353b4773188ee3d3acb4078363; 451d8123f89791bb628277c0bdb4cae34a3563e6 up to, but not including, 876f8ab52363f649bcc74072157dfd7adfbabc0d; 5.9 | ddf4e04e946aaa6c458b8b6829617cc44af2bffd, a1a485e45d24b1cd8fe834fd6f1b06e2903827da, 6086258bd5ea7b5c706ff62da42b8e271b2401db, 1787b9f0729d318d67cf7c5a95f0c3dba9a7cc18, d103fb6726904e353b4773188ee3d3acb4078363, 876f8ab52363f649bcc74072157dfd7adfbabc0d |
| Linux | Linux Kernel | 5.9 up to, but not including, 5.10.201; 5.11 up to, but not including, 5.15.139; 5.16 up to, but not including, 6.1.63; 6.2 up to, but not including, 6.5.12; 6.6 up to, but not including, 6.6.2 | 5.10.201, 5.15.139, 6.1.63, 6.5.12, 6.6.2 |
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
- HighData or code can be modified at will.
- 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:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: hsr: Prevent use after free in prp_create_tagged_frame() The prp_fill_rct() function can fail. In that situation, it frees the skb and returns NULL. Meanwhile on the success path, it returns the original skb. So it's straight forward to fix bug by using the returned value.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
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
Patches and release notes
- git.kernel.org/stable/c/1787b9f0729d318d67cf7c5a95f0c3dba9a7cc18
- git.kernel.org/stable/c/6086258bd5ea7b5c706ff62da42b8e271b2401db
- git.kernel.org/stable/c/876f8ab52363f649bcc74072157dfd7adfbabc0d
- git.kernel.org/stable/c/a1a485e45d24b1cd8fe834fd6f1b06e2903827da
- git.kernel.org/stable/c/d103fb6726904e353b4773188ee3d3acb4078363
- git.kernel.org/stable/c/ddf4e04e946aaa6c458b8b6829617cc44af2bffd
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 8.8 High severity
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