Linux: Use After Free
CVE-2024-50186 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 daf462ff3cde6ecf22b98d9ae770232c10d28de2, b7d22a79ff4e962b8af5ffe623abd1d6c179eb9f, 563e6892e21d6ecabdf62103fc4e7b326d212334 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 0.23% 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 daf462ff3cde6ecf22b98d9ae770232c10d28de2 or b7d22a79ff4e962b8af5ffe623abd1d6c179eb9f or 563e6892e21d6ecabdf62103fc4e7b326d212334 or 8e1b72fd74bf9da3b099d09857f4e7f114f38e12, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.168 or 6.1.113 or 6.6.57 or 6.10, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 78e4aa528a7b1204219d808310524344f627d069 up to, but not including, daf462ff3cde6ecf22b98d9ae770232c10d28de2; 893eeba94c40d513cd0fe6539330ebdaea208c0e up to, but not including, b7d22a79ff4e962b8af5ffe623abd1d6c179eb9f; 454c454ed645fed051216b79622f7cb69c1638f5 up to, but not including, 563e6892e21d6ecabdf62103fc4e7b326d212334; 6cd4a78d962bebbaf8beb7d2ead3f34120e3f7b2 up to, but not including, 8e1b72fd74bf9da3b099d09857f4e7f114f38e12; 6cd4a78d962bebbaf8beb7d2ead3f34120e3f7b2 up to, but not including, 631083143315d1b192bd7d915b967b37819e88ea; 5dfe2408fd7dc4d2e7ac38a116ff0a37b1cfd3b9; 5.15.162 up to, but not including, 5.15.168; 6.1.96 up to, but not including, 6.1.113; and 3 more ranges | daf462ff3cde6ecf22b98d9ae770232c10d28de2, b7d22a79ff4e962b8af5ffe623abd1d6c179eb9f, 563e6892e21d6ecabdf62103fc4e7b326d212334, 8e1b72fd74bf9da3b099d09857f4e7f114f38e12, 631083143315d1b192bd7d915b967b37819e88ea, 5.15.168 |
| Linux | Linux Kernel | 5.15.162 up to, but not including, 5.15.168; 6.1.96 up to, but not including, 6.1.113; 6.6.36 up to, but not including, 6.6.57; 6.9.7 up to, but not including, 6.10; 6.10 up to, but not including, 6.11.4; 6.12 | 5.15.168, 6.1.113, 6.6.57, 6.10, 6.11.4 |
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: net: explicitly clear the sk pointer, when pf->create fails We have recently noticed the exact same KASAN splat as in commit 6cd4a78d962b ("net: do not leave a dangling sk pointer, when socket creation fails"). The problem is that commit did not fully address the problem, as some pf->create implementations do not use sk_common_release in their error paths. For example, we can use the same reproducer as in the above commit, but changing ping to arping. arping uses AF_PACKET socket and if packet_create fails, it will just sk_free the allocated sk object. While we could chase all the pf->create implementations and make sure they NULL the freed sk object on error from the socket, we can't guarantee future protocols will not make the same mistake. So it is easier to just explicitly NULL the sk pointer upon return from pf->create in __sock_create. We do know that pf->create always releases the allocated sk object on error, so if the pointer is not NULL, it is definitely dangling.
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
- git.kernel.org/stable/c/563e6892e21d6ecabdf62103fc4e7b326d212334
- git.kernel.org/stable/c/631083143315d1b192bd7d915b967b37819e88ea
- git.kernel.org/stable/c/8e1b72fd74bf9da3b099d09857f4e7f114f38e12
- git.kernel.org/stable/c/b7d22a79ff4e962b8af5ffe623abd1d6c179eb9f
- git.kernel.org/stable/c/daf462ff3cde6ecf22b98d9ae770232c10d28de2
Other references
Recent Use After Free vulnerabilities
- 7.0 High severity
- 7.8 High severity
- 8.8 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
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