Linux: Use After Free
CVE-2022-50212 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 9e7dcb88ec8e85e4a8ad0ea494ea2f90f32d2583, 91501513016903077f91033fa5d2aa26cac399b2, 0f49613a213d918af790c1276f79da741968de11 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 0.24% 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 9e7dcb88ec8e85e4a8ad0ea494ea2f90f32d2583 or 91501513016903077f91033fa5d2aa26cac399b2 or 0f49613a213d918af790c1276f79da741968de11 or 58e863f64ee3d0879297e5e53b646e4b91e59620, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.137 or 5.15.61 or 5.18.18 or 5.19.2, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 837830a4b439bfeb86c70b0115c280377c84714b up to, but not including, 9e7dcb88ec8e85e4a8ad0ea494ea2f90f32d2583; 837830a4b439bfeb86c70b0115c280377c84714b up to, but not including, 91501513016903077f91033fa5d2aa26cac399b2; 837830a4b439bfeb86c70b0115c280377c84714b up to, but not including, 0f49613a213d918af790c1276f79da741968de11; 837830a4b439bfeb86c70b0115c280377c84714b up to, but not including, 58e863f64ee3d0879297e5e53b646e4b91e59620; 837830a4b439bfeb86c70b0115c280377c84714b up to, but not including, 95f466d22364a33d183509629d0879885b4f547e; 5.9 | 9e7dcb88ec8e85e4a8ad0ea494ea2f90f32d2583, 91501513016903077f91033fa5d2aa26cac399b2, 0f49613a213d918af790c1276f79da741968de11, 58e863f64ee3d0879297e5e53b646e4b91e59620, 95f466d22364a33d183509629d0879885b4f547e |
| Linux | Linux Kernel | 5.9 up to, but not including, 5.10.137; 5.11 up to, but not including, 5.15.61; 5.16 up to, but not including, 5.18.18; 5.19 up to, but not including, 5.19.2 | 5.10.137, 5.15.61, 5.18.18, 5.19.2 |
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: netfilter: nf_tables: do not allow CHAIN_ID to refer to another table When doing lookups for chains on the same batch by using its ID, a chain from a different table can be used. If a rule is added to a table but refers to a chain in a different table, it will be linked to the chain in table2, but would have expressions referring to objects in table1. Then, when table1 is removed, the rule will not be removed as its linked to a chain in table2. When expressions in the rule are processed or removed, that will lead to a use-after-free. When looking for chains by ID, use the table that was used for the lookup by name, and only return chains belonging to that same table.
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/0f49613a213d918af790c1276f79da741968de11
- git.kernel.org/stable/c/58e863f64ee3d0879297e5e53b646e4b91e59620
- git.kernel.org/stable/c/91501513016903077f91033fa5d2aa26cac399b2
- git.kernel.org/stable/c/95f466d22364a33d183509629d0879885b4f547e
- git.kernel.org/stable/c/9e7dcb88ec8e85e4a8ad0ea494ea2f90f32d2583
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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