Linux: Use After Free
CVE-2022-49076 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 5f54364ff6cfcd14cddf5441c4a490bb28dd69f7, 9ca11bd8222a612de0d2f54d050bfcf61ae2883f, 0b7186d657ee55e2cdefae498f07d5c1961e8023 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 0.26% 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 5f54364ff6cfcd14cddf5441c4a490bb28dd69f7 or 9ca11bd8222a612de0d2f54d050bfcf61ae2883f or 0b7186d657ee55e2cdefae498f07d5c1961e8023 or 5a9a1b24ddb510715f8f621263938186579a965c, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.111 or 5.15.34 or 5.16.20 or 5.17.3, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 3d2a9d642512c21a12d19b9250e7a835dcb41a79 up to, but not including, 5f54364ff6cfcd14cddf5441c4a490bb28dd69f7; 3d2a9d642512c21a12d19b9250e7a835dcb41a79 up to, but not including, 9ca11bd8222a612de0d2f54d050bfcf61ae2883f; 3d2a9d642512c21a12d19b9250e7a835dcb41a79 up to, but not including, 0b7186d657ee55e2cdefae498f07d5c1961e8023; 3d2a9d642512c21a12d19b9250e7a835dcb41a79 up to, but not including, 5a9a1b24ddb510715f8f621263938186579a965c; 3d2a9d642512c21a12d19b9250e7a835dcb41a79 up to, but not including, 2bbac98d0930e8161b1957dc0ec99de39ade1b3c; 5732f83596f8a573f2cde814cc76a54e1a8995c7; 5.9.12 up to, but not including, 5.10; 5.10 | 5f54364ff6cfcd14cddf5441c4a490bb28dd69f7, 9ca11bd8222a612de0d2f54d050bfcf61ae2883f, 0b7186d657ee55e2cdefae498f07d5c1961e8023, 5a9a1b24ddb510715f8f621263938186579a965c, 2bbac98d0930e8161b1957dc0ec99de39ade1b3c, 5.10 |
| Linux | Linux Kernel | 5.9.12 up to, but not including, 5.10.111; 5.11 up to, but not including, 5.15.34; 5.16 up to, but not including, 5.16.20; 5.17 up to, but not including, 5.17.3; 5.18 | 5.10.111, 5.15.34, 5.16.20, 5.17.3 |
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 CISA (ADP).
Official description
In the Linux kernel, the following vulnerability has been resolved: RDMA/hfi1: Fix use-after-free bug for mm struct Under certain conditions, such as MPI_Abort, the hfi1 cleanup code may represent the last reference held on the task mm. hfi1_mmu_rb_unregister() then drops the last reference and the mm is freed before the final use in hfi1_release_user_pages(). A new task may allocate the mm structure while it is still being used, resulting in problems. One manifestation is corruption of the mmap_sem counter leading to a hang in down_write(). Another is corruption of an mm struct that is in use by another task.
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.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/0b7186d657ee55e2cdefae498f07d5c1961e8023
- git.kernel.org/stable/c/2bbac98d0930e8161b1957dc0ec99de39ade1b3c
- git.kernel.org/stable/c/5a9a1b24ddb510715f8f621263938186579a965c
- git.kernel.org/stable/c/5f54364ff6cfcd14cddf5441c4a490bb28dd69f7
- git.kernel.org/stable/c/9ca11bd8222a612de0d2f54d050bfcf61ae2883f
Recent Use After Free vulnerabilities
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- 7.8 High severity
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- 7.8 High severity
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