Linux: Use After Free
CVE-2026-31589 is a critical-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions efc52947247a21bbf79059539bbbd40f4ea76f00, b667df39d98a7a24be7c2a40ff0863dac1ad2cd7, c330e65ea59c4805d6ab6757c4ddfe8c63acef31 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 0.44% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to efc52947247a21bbf79059539bbbd40f4ea76f00 or b667df39d98a7a24be7c2a40ff0863dac1ad2cd7 or c330e65ea59c4805d6ab6757c4ddfe8c63acef31 or 615d9bb2ccad42f9e21d837431e401db2e471195, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.19.14 or 7.0.1, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | fb7d3bc4149395c1ae99029c852eab6c28fc3c88 up to, but not including, efc52947247a21bbf79059539bbbd40f4ea76f00; fb7d3bc4149395c1ae99029c852eab6c28fc3c88 up to, but not including, b667df39d98a7a24be7c2a40ff0863dac1ad2cd7; fb7d3bc4149395c1ae99029c852eab6c28fc3c88 up to, but not including, c330e65ea59c4805d6ab6757c4ddfe8c63acef31; fb7d3bc4149395c1ae99029c852eab6c28fc3c88 up to, but not including, 615d9bb2ccad42f9e21d837431e401db2e471195; 6.14 | efc52947247a21bbf79059539bbbd40f4ea76f00, b667df39d98a7a24be7c2a40ff0863dac1ad2cd7, c330e65ea59c4805d6ab6757c4ddfe8c63acef31, 615d9bb2ccad42f9e21d837431e401db2e471195 |
| Linux | Linux Kernel | 6.14 up to, but not including, 6.19.14; 7.0 up to, but not including, 7.0.1 | 6.19.14, 7.0.1 |
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
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- 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:N/AC:L/PR:N/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: mm: call ->free_folio() directly in folio_unmap_invalidate() We can only call filemap_free_folio() if we have a reference to (or hold a lock on) the mapping. Otherwise, we've already removed the folio from the mapping so it no longer pins the mapping and the mapping can be removed, causing a use-after-free when accessing mapping->a_ops. Follow the same pattern as __remove_mapping() and load the free_folio function pointer before dropping the lock on the mapping. That lets us make filemap_free_folio() static as this was the only caller outside filemap.c.
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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
Recent Use After Free vulnerabilities
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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