Linux: Use After Free
CVE-2023-53426 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 5979985f2d6b565b6cf0f79a62670a2855c0e96c, 6436973164ea5506a495f39e56be5aea375e7832, 595931912357fa3507e522a7f8a0a76e423c23e4 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 0.15% 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 5979985f2d6b565b6cf0f79a62670a2855c0e96c or 6436973164ea5506a495f39e56be5aea375e7832 or 595931912357fa3507e522a7f8a0a76e423c23e4 or 3e019d8a05a38abb5c85d4f1e85fda964610aa14, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.132 or 5.17 or 6.1.54 or 6.5.4, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | ad7219cd8751bd258b9d1e69ae0654ec00f71875 up to, but not including, 5979985f2d6b565b6cf0f79a62670a2855c0e96c; 18b1ab7aa76bde181bdb1ab19a87fa9523c32f21 up to, but not including, 6436973164ea5506a495f39e56be5aea375e7832; 18b1ab7aa76bde181bdb1ab19a87fa9523c32f21 up to, but not including, 595931912357fa3507e522a7f8a0a76e423c23e4; 18b1ab7aa76bde181bdb1ab19a87fa9523c32f21 up to, but not including, 3e019d8a05a38abb5c85d4f1e85fda964610aa14; d1579253ffce39986e7a6ab757ac93b2680a665f; 8a2dea162b92c322f3e42eae0c4a74b8d20aa7a9; 5.15.33 up to, but not including, 5.15.132; 5.16.19 up to, but not including, 5.17; and 2 more ranges | 5979985f2d6b565b6cf0f79a62670a2855c0e96c, 6436973164ea5506a495f39e56be5aea375e7832, 595931912357fa3507e522a7f8a0a76e423c23e4, 3e019d8a05a38abb5c85d4f1e85fda964610aa14, 5.15.132, 5.17 |
| Linux | Linux Kernel | 5.15.33 up to, but not including, 5.15.132; 5.16.19 up to, but not including, 5.17; 5.17.2 up to, but not including, 6.1.54; 6.2 up to, but not including, 6.5.4 | 5.15.132, 5.17, 6.1.54, 6.5.4 |
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
- 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 | 7.8 | High | NVD |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: xsk: Fix xsk_diag use-after-free error during socket cleanup Fix a use-after-free error that is possible if the xsk_diag interface is used after the socket has been unbound from the device. This can happen either due to the socket being closed or the device disappearing. In the early days of AF_XDP, the way we tested that a socket was not bound to a device was to simply check if the netdevice pointer in the xsk socket structure was NULL. Later, a better system was introduced by having an explicit state variable in the xsk socket struct. For example, the state of a socket that is on the way to being closed and has been unbound from the device is XSK_UNBOUND. The commit in the Fixes tag below deleted the old way of signalling that a socket is unbound, setting dev to NULL. This in the belief that all code using the old way had been exterminated. That was unfortunately not true as the xsk diagnostics code was still using the old way and thus does not work as intended when a socket is going down. Fix this by introducing a test against the state variable. If the socket is in the state XSK_UNBOUND, simply abort the diagnostic's netlink operation.
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: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
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
- 7.8 High severity
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