Linux: Use After Free
CVE-2022-50072 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 0fffb46ff3d5ed4668aca96441ec7a25b793bd6f, f7ee3b772d9de87387a725caa04bc041ac7fe5ec, 76ffd2042438769298f34b76102b40dea89de616 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 0.21% 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 0fffb46ff3d5ed4668aca96441ec7a25b793bd6f or f7ee3b772d9de87387a725caa04bc041ac7fe5ec or 76ffd2042438769298f34b76102b40dea89de616 or a4cf3dadd1fa43609f7c6570c9116b0e0a9923d1, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.19.256 or 5.4.211 or 5.10.138 or 5.15.63, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 6b3fc1496e7227cd6a39a80bbfb7588ef7c7a010 up to, but not including, 0fffb46ff3d5ed4668aca96441ec7a25b793bd6f; a2b3be930e79cc5d9d829f158e31172b2043f0cd up to, but not including, f7ee3b772d9de87387a725caa04bc041ac7fe5ec; 0ee5b9644f06b4d3cdcd9544f43f63312e425a4c up to, but not including, 76ffd2042438769298f34b76102b40dea89de616; d4c2a041ed3ba114502d5ed6ace5b1a48d637a8e up to, but not including, a4cf3dadd1fa43609f7c6570c9116b0e0a9923d1; 6949493884fe88500de4af182588e071cf1544ee up to, but not including, b03d1117e9be7c7da60e466eaf9beed85c5916c8; 6949493884fe88500de4af182588e071cf1544ee up to, but not including, 2135e5d56278ffdb1c2e6d325dc6b87f669b9dac; 08d7a26d115cc7892668baa9750f64bd8baca29b; ea759ae0a9ae5acee677d722129710ac89cc59c1; and 7 more ranges | 0fffb46ff3d5ed4668aca96441ec7a25b793bd6f, f7ee3b772d9de87387a725caa04bc041ac7fe5ec, 76ffd2042438769298f34b76102b40dea89de616, a4cf3dadd1fa43609f7c6570c9116b0e0a9923d1, b03d1117e9be7c7da60e466eaf9beed85c5916c8, 2135e5d56278ffdb1c2e6d325dc6b87f669b9dac |
| Linux | Linux Kernel | 4.19.247 up to, but not including, 4.19.256; 5.4.198 up to, but not including, 5.4.211; 5.10.122 up to, but not including, 5.10.138; 5.15.47 up to, but not including, 5.15.63; 5.17.15 up to, but not including, 5.18; 5.18.4 up to, but not including, 5.19.4 | 4.19.256, 5.4.211, 5.10.138, 5.15.63, 5.18, 5.19.4 |
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 | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: NFSv4/pnfs: Fix a use-after-free bug in open If someone cancels the open RPC call, then we must not try to free either the open slot or the layoutget operation arguments, since they are likely still in use by the hung RPC call.
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/0fffb46ff3d5ed4668aca96441ec7a25b793bd6f
- git.kernel.org/stable/c/2135e5d56278ffdb1c2e6d325dc6b87f669b9dac
- git.kernel.org/stable/c/76ffd2042438769298f34b76102b40dea89de616
- git.kernel.org/stable/c/a4cf3dadd1fa43609f7c6570c9116b0e0a9923d1
- git.kernel.org/stable/c/b03d1117e9be7c7da60e466eaf9beed85c5916c8
- git.kernel.org/stable/c/f7ee3b772d9de87387a725caa04bc041ac7fe5ec
Recent Use After Free vulnerabilities
- 8.8 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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