Linux: Use After Free
CVE-2022-50274 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 ac521bbe3d00fa574e66a9361763f2b37725bc97, 219b44bf94203bd433aa91b7796475bf656348e5, 6d18b44bb44e1f4d97dfe0efe92ac0f0984739c2 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 0.16% 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 ac521bbe3d00fa574e66a9361763f2b37725bc97 or 219b44bf94203bd433aa91b7796475bf656348e5 or 6d18b44bb44e1f4d97dfe0efe92ac0f0984739c2 or 2abd73433872194bccdf1432a0980e4ec5273c2a, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.14.303 or 4.19.270 or 5.4.229 or 5.10.163, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, ac521bbe3d00fa574e66a9361763f2b37725bc97; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 219b44bf94203bd433aa91b7796475bf656348e5; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 6d18b44bb44e1f4d97dfe0efe92ac0f0984739c2; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 2abd73433872194bccdf1432a0980e4ec5273c2a; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 88a6f8a72d167294c0931c7874941bf37a41b6dd; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, a2f0a08aa613176c9688c81d7b598a7779974991; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 9945d05d6693710574f354c5dbddc47f5101eb77; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 0fc044b2b5e2d05a1fa1fb0d7f270367a7855d79; and 1 more ranges | ac521bbe3d00fa574e66a9361763f2b37725bc97, 219b44bf94203bd433aa91b7796475bf656348e5, 6d18b44bb44e1f4d97dfe0efe92ac0f0984739c2, 2abd73433872194bccdf1432a0980e4ec5273c2a, 88a6f8a72d167294c0931c7874941bf37a41b6dd, a2f0a08aa613176c9688c81d7b598a7779974991 |
| Linux | Linux Kernel | before 4.14.303; 4.15 up to, but not including, 4.19.270; 4.20 up to, but not including, 5.4.229; 5.5 up to, but not including, 5.10.163; 5.11 up to, but not including, 5.15.86; 5.16 up to, but not including, 6.0.16; 6.1 up to, but not including, 6.1.2 | 4.14.303, 4.19.270, 5.4.229, 5.10.163, 5.15.86, 6.0.16 |
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: media: dvbdev: adopts refcnt to avoid UAF dvb_unregister_device() is known that prone to use-after-free. That is, the cleanup from dvb_unregister_device() releases the dvb_device even if there are pointers stored in file->private_data still refer to it. This patch adds a reference counter into struct dvb_device and delays its deallocation until no pointer refers to the object.
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/0fc044b2b5e2d05a1fa1fb0d7f270367a7855d79
- git.kernel.org/stable/c/219b44bf94203bd433aa91b7796475bf656348e5
- git.kernel.org/stable/c/2abd73433872194bccdf1432a0980e4ec5273c2a
- git.kernel.org/stable/c/6d18b44bb44e1f4d97dfe0efe92ac0f0984739c2
- git.kernel.org/stable/c/88a6f8a72d167294c0931c7874941bf37a41b6dd
- git.kernel.org/stable/c/9945d05d6693710574f354c5dbddc47f5101eb77
- git.kernel.org/stable/c/a2f0a08aa613176c9688c81d7b598a7779974991
- git.kernel.org/stable/c/ac521bbe3d00fa574e66a9361763f2b37725bc97
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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