Linux: Double Free
CVE-2026-64383 is a critical-severity double 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 6e27f40b682a5e42a2daae3ce6d96f0e0e16dedb, 878757163eea684750107a31ea134c103863515d, 3407240cde132a4b72d6429a2625a09a2f78adaf 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 0.46% 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 6e27f40b682a5e42a2daae3ce6d96f0e0e16dedb or 878757163eea684750107a31ea134c103863515d or 3407240cde132a4b72d6429a2625a09a2f78adaf or 013a9a3da46c5dabcf18f65ea6a47874ba12a15d, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.145 or 6.12.96 or 6.18.39 or 7.1.4, 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 | 433042a91f9373241307725b52de573933ffedbf up to, but not including, 6e27f40b682a5e42a2daae3ce6d96f0e0e16dedb; 4f1fffa2376922f3d1d506e49c0fd445b023a28e up to, but not including, 878757163eea684750107a31ea134c103863515d; 4f1fffa2376922f3d1d506e49c0fd445b023a28e up to, but not including, 3407240cde132a4b72d6429a2625a09a2f78adaf; 4f1fffa2376922f3d1d506e49c0fd445b023a28e up to, but not including, 013a9a3da46c5dabcf18f65ea6a47874ba12a15d; 4f1fffa2376922f3d1d506e49c0fd445b023a28e up to, but not including, 4be31c943a3a27a5a0251dbb8f5cb89059ec3d5a; 6.6.32 up to, but not including, 6.6.145; 6.8 | 6e27f40b682a5e42a2daae3ce6d96f0e0e16dedb, 878757163eea684750107a31ea134c103863515d, 3407240cde132a4b72d6429a2625a09a2f78adaf, 013a9a3da46c5dabcf18f65ea6a47874ba12a15d, 4be31c943a3a27a5a0251dbb8f5cb89059ec3d5a, 6.6.145 |
| Linux | Linux Kernel | 6.6.32 up to, but not including, 6.6.145; 6.8.1 up to, but not including, 6.12.96; 6.13 up to, but not including, 6.18.39; 6.19 up to, but not including, 7.1.4; 6.8 | 6.6.145, 6.12.96, 6.18.39, 7.1.4 |
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: smb: client: fix double-free in SMB2_flush() replay SMB2_flush() keeps its response buffer bookkeeping across replay attempts. If a replayable flush response is received and the retry then fails before cifs_send_recv() stores a replacement response, flush_exit will free the stale response pointer a second time. Reinitialize resp_buftype and rsp_iov at the top of the replay loop so cleanup only acts on response state produced by the current attempt. This fixes a double-free without changing replay handling for successful requests.
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.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/013a9a3da46c5dabcf18f65ea6a47874ba12a15d
- git.kernel.org/stable/c/3407240cde132a4b72d6429a2625a09a2f78adaf
- git.kernel.org/stable/c/4be31c943a3a27a5a0251dbb8f5cb89059ec3d5a
- git.kernel.org/stable/c/6e27f40b682a5e42a2daae3ce6d96f0e0e16dedb
- git.kernel.org/stable/c/878757163eea684750107a31ea134c103863515d
Recent Double Free vulnerabilities
- 7.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
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