Linux: Use After Free
CVE-2022-49770 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 274e4c79a3a2a24fba7cfe0e41113f1138785c37, cb7495fe957526555782ce0723f79ce92a6db22e, 044bc6d3c2c0e9090b0841e7b723875756534b45 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 0.58% 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 274e4c79a3a2a24fba7cfe0e41113f1138785c37 or cb7495fe957526555782ce0723f79ce92a6db22e or 044bc6d3c2c0e9090b0841e7b723875756534b45 or 2f6e2de3a5289004650118b61f138fe7c28e1905, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.19.268 or 5.4.226 or 5.10.157 or 5.15.81, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 982d6011bc30a26e8a3d546e0e7fc7db2c255d85 up to, but not including, 274e4c79a3a2a24fba7cfe0e41113f1138785c37; 982d6011bc30a26e8a3d546e0e7fc7db2c255d85 up to, but not including, cb7495fe957526555782ce0723f79ce92a6db22e; 982d6011bc30a26e8a3d546e0e7fc7db2c255d85 up to, but not including, 044bc6d3c2c0e9090b0841e7b723875756534b45; 982d6011bc30a26e8a3d546e0e7fc7db2c255d85 up to, but not including, 2f6e2de3a5289004650118b61f138fe7c28e1905; 982d6011bc30a26e8a3d546e0e7fc7db2c255d85 up to, but not including, fd879c83e87735ab8f00ef7755752cf0cbae24b2; 982d6011bc30a26e8a3d546e0e7fc7db2c255d85 up to, but not including, 51884d153f7ec85e18d607b2467820a90e0f4359; 4.0 | 274e4c79a3a2a24fba7cfe0e41113f1138785c37, cb7495fe957526555782ce0723f79ce92a6db22e, 044bc6d3c2c0e9090b0841e7b723875756534b45, 2f6e2de3a5289004650118b61f138fe7c28e1905, fd879c83e87735ab8f00ef7755752cf0cbae24b2, 51884d153f7ec85e18d607b2467820a90e0f4359 |
| Linux | Linux Kernel | 2.6.35 up to, but not including, 4.19.268; 4.20 up to, but not including, 5.4.226; 5.5 up to, but not including, 5.10.157; 5.11 up to, but not including, 5.15.81; 5.16 up to, but not including, 6.0.10; 2.6.34; 6.1 | 4.19.268, 5.4.226, 5.10.157, 5.15.81, 6.0.10 |
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 | 9.8 | Critical | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: ceph: avoid putting the realm twice when decoding snaps fails When decoding the snaps fails it maybe leaving the 'first_realm' and 'realm' pointing to the same snaprealm memory. And then it'll put it twice and could cause random use-after-free, BUG_ON, etc issues.
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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/044bc6d3c2c0e9090b0841e7b723875756534b45
- git.kernel.org/stable/c/274e4c79a3a2a24fba7cfe0e41113f1138785c37
- git.kernel.org/stable/c/2f6e2de3a5289004650118b61f138fe7c28e1905
- git.kernel.org/stable/c/51884d153f7ec85e18d607b2467820a90e0f4359
- git.kernel.org/stable/c/cb7495fe957526555782ce0723f79ce92a6db22e
- git.kernel.org/stable/c/fd879c83e87735ab8f00ef7755752cf0cbae24b2
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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