Linux: Double Free
CVE-2025-39870 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 25e6146c2812487a88f619d5ff6efbdcd5b2bc31, df82c7901513fd0fc738052a8e6a330d92cc8ec9, ec5430d090d0b6ace8fefa290fc37e88930017d2 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 0.16% 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 25e6146c2812487a88f619d5ff6efbdcd5b2bc31 or df82c7901513fd0fc738052a8e6a330d92cc8ec9 or ec5430d090d0b6ace8fefa290fc37e88930017d2 or 9f0e225635475b2285b966271d5e82cba74295b1, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.153 or 6.6.107 or 6.12.48 or 6.15, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | d584acdf54f409cb7eae1359ae6c12aaabedeed8 up to, but not including, 25e6146c2812487a88f619d5ff6efbdcd5b2bc31; 47846211998a9ffb0fcc08092eb95ac783d2b11a up to, but not including, df82c7901513fd0fc738052a8e6a330d92cc8ec9; 5fcd392dae6d6aba7dc64ffdbb838ff191315da3 up to, but not including, ec5430d090d0b6ace8fefa290fc37e88930017d2; 3fd2f4bc010cdfbc07dd21018dc65bd9370eb7a4 up to, but not including, 9f0e225635475b2285b966271d5e82cba74295b1; 3fd2f4bc010cdfbc07dd21018dc65bd9370eb7a4 up to, but not including, 39aaa337449e71a41d4813be0226a722827ba606; ed2c66000aa64c0d2621864831f0d04c820a1441; 6.1.140 up to, but not including, 6.1.153; 6.6.92 up to, but not including, 6.6.107; and 3 more ranges | 25e6146c2812487a88f619d5ff6efbdcd5b2bc31, df82c7901513fd0fc738052a8e6a330d92cc8ec9, ec5430d090d0b6ace8fefa290fc37e88930017d2, 9f0e225635475b2285b966271d5e82cba74295b1, 39aaa337449e71a41d4813be0226a722827ba606, 6.1.153 |
| Linux | Linux Kernel | 6.1.140 up to, but not including, 6.1.153; 6.6.92 up to, but not including, 6.6.107; 6.12.30 up to, but not including, 6.12.48; 6.14.8 up to, but not including, 6.15; 6.15.1 up to, but not including, 6.16.8; 6.15; 6.17 | 6.1.153, 6.6.107, 6.12.48, 6.15, 6.16.8 |
| Debian | Debian Linux | 11.0 | 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.
Official description
In the Linux kernel, the following vulnerability has been resolved: dmaengine: idxd: Fix double free in idxd_setup_wqs() The clean up in idxd_setup_wqs() has had a couple bugs because the error handling is a bit subtle. It's simpler to just re-write it in a cleaner way. The issues here are: 1) If "idxd->max_wqs" is <= 0 then we call put_device(conf_dev) when "conf_dev" hasn't been initialized. 2) If kzalloc_node() fails then again "conf_dev" is invalid. It's either uninitialized or it points to the "conf_dev" from the previous iteration so it leads to a double free. It's better to free partial loop iterations within the loop and then the unwinding at the end can handle whole loop iterations. I also renamed the labels to describe what the goto does and not where the goto was located.
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
- git.kernel.org/stable/c/25e6146c2812487a88f619d5ff6efbdcd5b2bc31
- git.kernel.org/stable/c/39aaa337449e71a41d4813be0226a722827ba606
- git.kernel.org/stable/c/9f0e225635475b2285b966271d5e82cba74295b1
- git.kernel.org/stable/c/df82c7901513fd0fc738052a8e6a330d92cc8ec9
- git.kernel.org/stable/c/ec5430d090d0b6ace8fefa290fc37e88930017d2
Third-party and government advisories
- lists.debian.org/debian-lts-announce/2025/10/msg00008.htmlMailing List, Third Party Advisory
Recent Double Free vulnerabilities
- 7.8 High 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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