Linux: Double Free
CVE-2026-43128 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 70542b69abff34d24b11ae0bb200cc7a766d18df, b324327ff6f48d8065dca67eb3b91357e72726bd, ba3bf0f1bf1d5d0404678485e872980532fcc2c4 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 0.14% 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 70542b69abff34d24b11ae0bb200cc7a766d18df or b324327ff6f48d8065dca67eb3b91357e72726bd or ba3bf0f1bf1d5d0404678485e872980532fcc2c4 or d3e32e2f3262f1b25d77c085ace38e2cc4ad75cf, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.165 or 6.6.128 or 6.12.75 or 6.18.16, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 1e4df4a21c5ac722df1099eee30cad9246c889b5 up to, but not including, 70542b69abff34d24b11ae0bb200cc7a766d18df; 1e4df4a21c5ac722df1099eee30cad9246c889b5 up to, but not including, b324327ff6f48d8065dca67eb3b91357e72726bd; 1e4df4a21c5ac722df1099eee30cad9246c889b5 up to, but not including, ba3bf0f1bf1d5d0404678485e872980532fcc2c4; 1e4df4a21c5ac722df1099eee30cad9246c889b5 up to, but not including, d3e32e2f3262f1b25d77c085ace38e2cc4ad75cf; 1e4df4a21c5ac722df1099eee30cad9246c889b5 up to, but not including, 40126bcbefa79ea86672e05dae608596bab38319; 1e4df4a21c5ac722df1099eee30cad9246c889b5 up to, but not including, 104016eb671e19709721c1b0048dd912dc2e96be; 5.16 | 70542b69abff34d24b11ae0bb200cc7a766d18df, b324327ff6f48d8065dca67eb3b91357e72726bd, ba3bf0f1bf1d5d0404678485e872980532fcc2c4, d3e32e2f3262f1b25d77c085ace38e2cc4ad75cf, 40126bcbefa79ea86672e05dae608596bab38319, 104016eb671e19709721c1b0048dd912dc2e96be |
| Linux | Linux Kernel | 5.16 up to, but not including, 6.1.165; 6.2 up to, but not including, 6.6.128; 6.7 up to, but not including, 6.12.75; 6.13 up to, but not including, 6.18.16; 6.19 up to, but not including, 6.19.6; 7.0 | 6.1.165, 6.6.128, 6.12.75, 6.18.16, 6.19.6 |
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: RDMA/umem: Fix double dma_buf_unpin in failure path In ib_umem_dmabuf_get_pinned_with_dma_device(), the call to ib_umem_dmabuf_map_pages() can fail. If this occurs, the dmabuf is immediately unpinned but the umem_dmabuf->pinned flag is still set. Then, when ib_umem_release() is called, it calls ib_umem_dmabuf_revoke() which will call dma_buf_unpin() again. Fix this by removing the immediate unpin upon failure and just let the ib_umem_release/revoke path handle it. This also ensures the proper unmap-unpin unwind ordering if the dmabuf_map_pages call happened to fail due to dma_resv_wait_timeout (and therefore has a non-NULL umem_dmabuf->sgt).
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: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/104016eb671e19709721c1b0048dd912dc2e96be
- git.kernel.org/stable/c/40126bcbefa79ea86672e05dae608596bab38319
- git.kernel.org/stable/c/70542b69abff34d24b11ae0bb200cc7a766d18df
- git.kernel.org/stable/c/b324327ff6f48d8065dca67eb3b91357e72726bd
- git.kernel.org/stable/c/ba3bf0f1bf1d5d0404678485e872980532fcc2c4
- git.kernel.org/stable/c/d3e32e2f3262f1b25d77c085ace38e2cc4ad75cf
Recent Double Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
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