Linux Kernel Use-After-Free
CVE-2024-1086 is a high-severity use after free vulnerability in Kernel from 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 version 6.8 as the first without the flaw, so updating Kernel to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on May 30, 2024, which means attacks have been observed in the wild, including in ransomware campaigns.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Kernel to 6.8 or a later version.
- Update linux_kernel to 6.8 or a later version.
- CISA's required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Kernel | 3.15 up to, but not including, 6.8 | 6.8 |
| Linux | linux_kernel | 3.15 up to, but not including, 6.8 | 6.8 |
| NetApp | H300s Firmware | Not specified in the record | Not stated |
| NetApp | H500s Firmware | Not specified in the record | Not stated |
| NetApp | H700s Firmware | Not specified in the record | Not stated |
| NetApp | H410s Firmware | Not specified in the record | Not stated |
| NetApp | H410c Firmware | Not specified in the record | Not stated |
| NetApp | Bootstrap OS | Not specified in the record | Not stated |
| Fedora Project | Fedora | 39 | Not stated |
| Red Hat | Enterprise Linux Desktop | 7.0 | Not stated |
| Red Hat | Enterprise Linux For IBM Z Systems | 7.0_s390x | Not stated |
| Red Hat | Enterprise Linux For Power Big Endian | 7.0_ppc64 | Not stated |
| Red Hat | Enterprise Linux For Power Little Endian | 7.0_ppc64le | Not stated |
| Red Hat | Enterprise Linux Server | 7.0 | Not stated |
| Red Hat | Enterprise Linux Workstation | 7.0 | Not stated |
| Debian | Debian Linux | 10.0 | Not stated |
| NetApp | A250 Firmware | Not specified in the record | Not stated |
| NetApp | 500f Firmware | Not specified in the record | Not stated |
| NetApp | C250 Firmware | Not specified in the record | Not stated |
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 (google.com) |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
A use-after-free vulnerability in the Linux kernel's netfilter: nf_tables component can be exploited to achieve local privilege escalation. The nft_verdict_init() function allows positive values as drop error within the hook verdict, and hence the nf_hook_slow() function can cause a double free vulnerability when NF_DROP is issued with a drop error which resembles NF_ACCEPT. We recommend upgrading past commit f342de4e2f33e0e39165d8639387aa6c19dff660.
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.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
- Deadline for US federal agencies to remediate, set by CISA.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Third-party and government advisories
- security.netapp.com/advisory/ntap-20240614-0009/Third Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-1086US Government Resource
Technical write-ups (may include proof of concept)
- openwall.com/lists/oss-security/2024/04/14/1Exploit, Mailing List
- openwall.com/lists/oss-security/2024/04/17/5Exploit, Mailing List
- github.com/Notselwyn/CVE-2024-1086Exploit, Third Party Advisory
- pwning.tech/nftables/Exploit, Technical Description, Third Party Advisory
Other references
- openwall.com/lists/oss-security/2024/04/15/2Mailing List
- lists.debian.org/debian-lts-announce/2024/06/msg00016.htmlMailing List
- lists.debian.org/debian-lts-announce/2024/06/msg00020.htmlMailing List
- lists.fedoraproject.org/archives/list/[email protected]/message/7LSPIOMIJYTLZB6QKPQVVA…Mailing List
- news.ycombinator.com/item?id=39828424Issue Tracking
Other vulnerabilities in Kernel
- 7.1 High severity
- 7.8 High severity
- 7.1 High severity
- 7.4 High severity
- 7.0 High severity
- 7.8 High severity
Recent Use After Free vulnerabilities
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 7.8 High severity
- 8.8 High severity
- 8.8 High severity
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