Linux: Double Free
CVE-2026-31471 is a high-severity double 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 371a43c4ac70cac0de9f9b1fc5b1660b9565b9f1, 5784a1e2889c9525a8f036cb586930e232170bf7, d849a2f7309fc0616e79d13b008b0a47e0458b6e 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 0.13% 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 371a43c4ac70cac0de9f9b1fc5b1660b9565b9f1 or 5784a1e2889c9525a8f036cb586930e232170bf7 or d849a2f7309fc0616e79d13b008b0a47e0458b6e, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.18.21 or 6.19.11, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 6be02e3e4f376fea468846c8562655ca5ee18204 up to, but not including, 371a43c4ac70cac0de9f9b1fc5b1660b9565b9f1; 6be02e3e4f376fea468846c8562655ca5ee18204 up to, but not including, 5784a1e2889c9525a8f036cb586930e232170bf7; 6be02e3e4f376fea468846c8562655ca5ee18204 up to, but not including, d849a2f7309fc0616e79d13b008b0a47e0458b6e; 6.14 | 371a43c4ac70cac0de9f9b1fc5b1660b9565b9f1, 5784a1e2889c9525a8f036cb586930e232170bf7, d849a2f7309fc0616e79d13b008b0a47e0458b6e |
| Linux | Linux Kernel | 6.14 up to, but not including, 6.18.21; 6.19 up to, but not including, 6.19.11; 7.0 | 6.18.21, 6.19.11 |
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 CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: xfrm: iptfs: only publish mode_data after clone setup iptfs_clone_state() stores x->mode_data before allocating the reorder window. If that allocation fails, the code frees the cloned state and returns -ENOMEM, leaving x->mode_data pointing at freed memory. The xfrm clone unwind later runs destroy_state() through x->mode_data, so the failed clone path tears down IPTFS state that clone_state() already freed. Keep the cloned IPTFS state private until all allocations succeed so failed clones leave x->mode_data unset. The destroy path already handles a NULL mode_data pointer.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Double Free
The product calls free() twice on the same memory address.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
- Use a static analysis tool to find double free instances.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Double Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 9.8 Critical severity
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