Linux: Use After Free
CVE-2022-50492 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 0a30a47741b6df1f9555a0fac6aebb7e8c363bad, 6808abdb33bf90330e70a687d29f038507e06ebb 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 0a30a47741b6df1f9555a0fac6aebb7e8c363bad or 6808abdb33bf90330e70a687d29f038507e06ebb, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.0.7 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | a3376e3ec81c5dd0622cbc187db76d2824d31c1c up to, but not including, 0a30a47741b6df1f9555a0fac6aebb7e8c363bad; a3376e3ec81c5dd0622cbc187db76d2824d31c1c up to, but not including, 6808abdb33bf90330e70a687d29f038507e06ebb; 3.12 | 0a30a47741b6df1f9555a0fac6aebb7e8c363bad, 6808abdb33bf90330e70a687d29f038507e06ebb |
| Linux | Linux Kernel | 3.12 up to, but not including, 6.0.7; 6.1 | 6.0.7 |
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: drm/msm: fix use-after-free on probe deferral The bridge counter was never reset when tearing down the DRM device so that stale pointers to deallocated structures would be accessed on the next tear down (e.g. after a second late bind deferral). Given enough bridges and a few probe deferrals this could currently also lead to data beyond the bridge array being corrupted. Patchwork: https://patchwork.freedesktop.org/patch/502665/
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
Recent Use After Free vulnerabilities
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- 7.8 High severity
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