Linux: Use After Free
CVE-2023-52509 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 65d34cfd4e347054eb4193bc95d9da7eaa72dee5, db9aafa19547833240f58c2998aed7baf414dc82, 616761cf9df9af838c0a1a1232a69322a9eb67e6 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 0.24% 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 65d34cfd4e347054eb4193bc95d9da7eaa72dee5 or db9aafa19547833240f58c2998aed7baf414dc82 or 616761cf9df9af838c0a1a1232a69322a9eb67e6 or 6f6fa8061f756aedb93af12a8a5d3cf659127965, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.4.259 or 5.10.199 or 5.15.136 or 6.1.59, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | c156633f1353264634135dea86ffcae74f2122fc up to, but not including, 65d34cfd4e347054eb4193bc95d9da7eaa72dee5; c156633f1353264634135dea86ffcae74f2122fc up to, but not including, db9aafa19547833240f58c2998aed7baf414dc82; c156633f1353264634135dea86ffcae74f2122fc up to, but not including, 616761cf9df9af838c0a1a1232a69322a9eb67e6; c156633f1353264634135dea86ffcae74f2122fc up to, but not including, 6f6fa8061f756aedb93af12a8a5d3cf659127965; c156633f1353264634135dea86ffcae74f2122fc up to, but not including, 105abd68ad8f781985113aee2e92e0702b133705; c156633f1353264634135dea86ffcae74f2122fc up to, but not including, 3971442870713de527684398416970cf025b4f89; 4.2 | 65d34cfd4e347054eb4193bc95d9da7eaa72dee5, db9aafa19547833240f58c2998aed7baf414dc82, 616761cf9df9af838c0a1a1232a69322a9eb67e6, 6f6fa8061f756aedb93af12a8a5d3cf659127965, 105abd68ad8f781985113aee2e92e0702b133705, 3971442870713de527684398416970cf025b4f89 |
| Linux | Linux Kernel | 4.2 up to, but not including, 5.4.259; 5.5 up to, but not including, 5.10.199; 5.11 up to, but not including, 5.15.136; 5.16 up to, but not including, 6.1.59; 6.2 up to, but not including, 6.5.8; 6.6 | 5.4.259, 5.10.199, 5.15.136, 6.1.59, 6.5.8 |
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 | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: ravb: Fix use-after-free issue in ravb_tx_timeout_work() The ravb_stop() should call cancel_work_sync(). Otherwise, ravb_tx_timeout_work() is possible to use the freed priv after ravb_remove() was called like below: CPU0 CPU1 ravb_tx_timeout() ravb_remove() unregister_netdev() free_netdev(ndev) // free priv ravb_tx_timeout_work() // use priv unregister_netdev() will call .ndo_stop() so that ravb_stop() is called. And, after phy_stop() is called, netif_carrier_off() is also called. So that .ndo_tx_timeout() will not be called after phy_stop().
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/105abd68ad8f781985113aee2e92e0702b133705
- git.kernel.org/stable/c/3971442870713de527684398416970cf025b4f89
- git.kernel.org/stable/c/616761cf9df9af838c0a1a1232a69322a9eb67e6
- git.kernel.org/stable/c/65d34cfd4e347054eb4193bc95d9da7eaa72dee5
- git.kernel.org/stable/c/6f6fa8061f756aedb93af12a8a5d3cf659127965
- git.kernel.org/stable/c/db9aafa19547833240f58c2998aed7baf414dc82
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.0 High severity
- 7.8 High severity
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