Linux: Use After Free
CVE-2024-49855 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.0 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 9c25faf72d780a9c71081710cd48759d61ff6e9b, 6e73b946a379a1dfbb62626af93843bdfb53753d, 5236ada8ebbd9e7461f17477357582f5be4f46f7 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 0.47% 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 9c25faf72d780a9c71081710cd48759d61ff6e9b or 6e73b946a379a1dfbb62626af93843bdfb53753d or 5236ada8ebbd9e7461f17477357582f5be4f46f7 or 9a74c3e6c0d686c26ba2aab66d15ddb89dc139cc, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.19 or 6.1.113 or 6.6.54 or 6.10.13, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 2895f1831e911ca87d4efdf43e35eb72a0c7e66e up to, but not including, 9c25faf72d780a9c71081710cd48759d61ff6e9b; 2895f1831e911ca87d4efdf43e35eb72a0c7e66e up to, but not including, 6e73b946a379a1dfbb62626af93843bdfb53753d; 2895f1831e911ca87d4efdf43e35eb72a0c7e66e up to, but not including, 5236ada8ebbd9e7461f17477357582f5be4f46f7; 2895f1831e911ca87d4efdf43e35eb72a0c7e66e up to, but not including, 9a74c3e6c0d686c26ba2aab66d15ddb89dc139cc; 2895f1831e911ca87d4efdf43e35eb72a0c7e66e up to, but not including, c9ea57c91f03bcad415e1a20113bdb2077bcf990; cdf62c535a9bfd5ff0eef4b91669da39d8abc0c3; 5171ef20bae852ff38f4cfdb368bcdcc744776d0; 5.17.15 up to, but not including, 5.18; and 2 more ranges | 9c25faf72d780a9c71081710cd48759d61ff6e9b, 6e73b946a379a1dfbb62626af93843bdfb53753d, 5236ada8ebbd9e7461f17477357582f5be4f46f7, 9a74c3e6c0d686c26ba2aab66d15ddb89dc139cc, c9ea57c91f03bcad415e1a20113bdb2077bcf990, 5.18 |
| Linux | Linux Kernel | 5.18.4 up to, but not including, 5.19; 5.19 up to, but not including, 6.1.113; 6.2 up to, but not including, 6.6.54; 6.7 up to, but not including, 6.10.13; 6.11 up to, but not including, 6.11.2; 5.17.15 | 5.19, 6.1.113, 6.6.54, 6.10.13, 6.11.2 |
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
- HighSuccess depends on conditions outside the attacker's control.
- 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:H/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.8 | Critical | CNA |
| CVSS 3.1 | 7.0 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: nbd: fix race between timeout and normal completion If request timetout is handled by nbd_requeue_cmd(), normal completion has to be stopped for avoiding to complete this requeued request, other use-after-free can be triggered. Fix the race by clearing NBD_CMD_INFLIGHT in nbd_requeue_cmd(), meantime make sure that cmd->lock is grabbed for clearing the flag and the requeue.
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: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/5236ada8ebbd9e7461f17477357582f5be4f46f7
- git.kernel.org/stable/c/6e73b946a379a1dfbb62626af93843bdfb53753d
- git.kernel.org/stable/c/9a74c3e6c0d686c26ba2aab66d15ddb89dc139cc
- git.kernel.org/stable/c/9c25faf72d780a9c71081710cd48759d61ff6e9b
- git.kernel.org/stable/c/c9ea57c91f03bcad415e1a20113bdb2077bcf990
Other references
Recent Use After Free vulnerabilities
- 7.0 High severity
- 7.0 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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