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

Status: published. Published: 2026-08-12. Updated: 2026-11-06.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ 57a304cfd43b2b4a5b44b8f5dc026abb34183068; < 29d9746812d8b7c37d594f484e994fd552c3ec33 (affected, git); ≥ 57a304cfd43b2b4a5b44b8f5dc026abb34183068; < b7c5b8e1d5f0779dfbabc3068b7ac0f12e53b3a8 (affected, git); ≥ 57a304cfd43b2b4a5b44b8f5dc026abb34183068; < 92bedc0455552b42ada1a1f42b0e3a8593cdfccc (affected, git); ≥ 57a304cfd43b2b4a5b44b8f5dc026abb34183068; < 14a8be9428435ee17f17fae7991215c246b7fd43 (affected, git); ≥ 57a304cfd43b2b4a5b44b8f5dc026abb34183068; < 797dc567146c7e3c4f8d9680e4fbc76e0a6d9151 (affected, git); ≥ 57a304cfd43b2b4a5b44b8f5dc026abb34183068; < ae0629ff9ccb836416ada129f4edc7efea6eaaad (affected, git); ≥ 57a304cfd43b2b4a5b44b8f5dc026abb34183068; < 6a8269b6459ed870a8156c106a0f597383907872 (affected, git). Source: CNA: Linux
- Linux / Linux: 5.13 (affected); ≥ 0; < 5.13 (unaffected, semver); ≥ 5.15.216; ≤ 5.15.* (unaffected, semver); ≥ 6.1.183; ≤ 6.1.* (unaffected, semver); ≥ 6.6.148; ≤ 6.6.* (unaffected, semver); ≥ 6.12.101; ≤ 6.12.* (unaffected, semver); ≥ 6.18.42; ≤ 6.18.* (unaffected, semver); ≥ 7.1.6; ≤ 7.1.* (unaffected, semver); ≥ 7.2; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: 0.16% as of 2026-11-06; percentile 5.36%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/29d9746812d8b7c37d594f484e994fd552c3ec33 (CNA: Linux)

- https://git.kernel.org/stable/c/b7c5b8e1d5f0779dfbabc3068b7ac0f12e53b3a8 (CNA: Linux)

- https://git.kernel.org/stable/c/92bedc0455552b42ada1a1f42b0e3a8593cdfccc (CNA: Linux)

- https://git.kernel.org/stable/c/14a8be9428435ee17f17fae7991215c246b7fd43 (CNA: Linux)

- https://git.kernel.org/stable/c/797dc567146c7e3c4f8d9680e4fbc76e0a6d9151 (CNA: Linux)

- https://git.kernel.org/stable/c/ae0629ff9ccb836416ada129f4edc7efea6eaaad (CNA: Linux)

- https://git.kernel.org/stable/c/6a8269b6459ed870a8156c106a0f597383907872 (CNA: Linux)

- https://git.kernel.org/stable/c/14a8be9428435ee17f17fae7991215c246b7fd43 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/29d9746812d8b7c37d594f484e994fd552c3ec33 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/6a8269b6459ed870a8156c106a0f597383907872 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/797dc567146c7e3c4f8d9680e4fbc76e0a6d9151 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/92bedc0455552b42ada1a1f42b0e3a8593cdfccc (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/ae0629ff9ccb836416ada129f4edc7efea6eaaad (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/b7c5b8e1d5f0779dfbabc3068b7ac0f12e53b3a8 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-68450; retrieved 2026-11-06; source updated 2026-11-06

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68450; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-68450; retrieved 2026-11-06; source updated Not reported

Revision: 92d26b11ad28c7ea9c181a06d1f7ef1732617c2d5d407d4637d28eda8d7e82bb

Canonical: https://y2.dev/cve/CVE-2026-68450

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.