Linux: Use After Free
CVE-2026-23001 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 8133e85b8a3ec9f10d861e0002ec6037256e987e, 484919832e2db6ce1e8add92c469e5d459a516b5, 232afc74a6dde0fe1830988e5827921f5ec9bb3f 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 8133e85b8a3ec9f10d861e0002ec6037256e987e or 484919832e2db6ce1e8add92c469e5d459a516b5 or 232afc74a6dde0fe1830988e5827921f5ec9bb3f or 15f6faf36e162532bec5cc05eb3fc622108bf2ed, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.249 or 5.15.199 or 6.1.162 or 6.6.122, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 79cf79abce71eb7dbc40e2f3121048ca5405cb47 up to, but not including, 8133e85b8a3ec9f10d861e0002ec6037256e987e; 79cf79abce71eb7dbc40e2f3121048ca5405cb47 up to, but not including, 484919832e2db6ce1e8add92c469e5d459a516b5; 79cf79abce71eb7dbc40e2f3121048ca5405cb47 up to, but not including, 232afc74a6dde0fe1830988e5827921f5ec9bb3f; 79cf79abce71eb7dbc40e2f3121048ca5405cb47 up to, but not including, 15f6faf36e162532bec5cc05eb3fc622108bf2ed; 79cf79abce71eb7dbc40e2f3121048ca5405cb47 up to, but not including, 8518712a2ca952d6da2238c6f0a16b4ae5ea3f13; 79cf79abce71eb7dbc40e2f3121048ca5405cb47 up to, but not including, 6dbead9c7677186f22b7981dd085a0feec1f038e; 79cf79abce71eb7dbc40e2f3121048ca5405cb47 up to, but not including, 7470a7a63dc162f07c26dbf960e41ee1e248d80e; 3.18 | 8133e85b8a3ec9f10d861e0002ec6037256e987e, 484919832e2db6ce1e8add92c469e5d459a516b5, 232afc74a6dde0fe1830988e5827921f5ec9bb3f, 15f6faf36e162532bec5cc05eb3fc622108bf2ed, 8518712a2ca952d6da2238c6f0a16b4ae5ea3f13, 6dbead9c7677186f22b7981dd085a0feec1f038e |
| Linux | Linux Kernel | 3.18.1 up to, but not including, 5.10.249; 5.11 up to, but not including, 5.15.199; 5.16 up to, but not including, 6.1.162; 6.2 up to, but not including, 6.6.122; 6.7 up to, but not including, 6.12.67; 6.13 up to, but not including, 6.18.7; 3.18; 6.19 | 5.10.249, 5.15.199, 6.1.162, 6.6.122, 6.12.67, 6.18.7 |
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: macvlan: fix possible UAF in macvlan_forward_source() Add RCU protection on (struct macvlan_source_entry)->vlan. Whenever macvlan_hash_del_source() is called, we must clear entry->vlan pointer before RCU grace period starts. This allows macvlan_forward_source() to skip over entries queued for freeing. Note that macvlan_dev are already RCU protected, as they are embedded in a standard netdev (netdev_priv(ndev)). https: //lore.kernel.org/netdev/[email protected]/T/#u
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/15f6faf36e162532bec5cc05eb3fc622108bf2ed
- git.kernel.org/stable/c/232afc74a6dde0fe1830988e5827921f5ec9bb3f
- git.kernel.org/stable/c/484919832e2db6ce1e8add92c469e5d459a516b5
- git.kernel.org/stable/c/6dbead9c7677186f22b7981dd085a0feec1f038e
- git.kernel.org/stable/c/7470a7a63dc162f07c26dbf960e41ee1e248d80e
- git.kernel.org/stable/c/8133e85b8a3ec9f10d861e0002ec6037256e987e
- git.kernel.org/stable/c/8518712a2ca952d6da2238c6f0a16b4ae5ea3f13
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 9.8 Critical severity
- 7.8 High severity
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