# CVE-2026-31535: smb: client: make use of smbdirect_socket.recv_io.credits.available

Status: published. Published: 2026-04-24. Updated: 2026-11-05.

In the Linux kernel, the following vulnerability has been resolved:

smb: client: make use of smbdirect_socket.recv_io.credits.available

The logic off managing recv credits by counting posted recv_io and
granted credits is racy.

That's because the peer might already consumed a credit,
but between receiving the incoming recv at the hardware
and processing the completion in the 'recv_done' functions
we likely have a window where we grant credits, which
don't really exist.

So we better have a decicated counter for the
available credits, which will be incremented
when we posted new recv buffers and drained when
we grant the credits to the peer.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ 5fb9b459b3686e366640edd4e62805ef7b4de927; < f664e6e8a81103cb45c8802a9bc7499e0902c458 (affected, git); ≥ 5fb9b459b3686e366640edd4e62805ef7b4de927; < be8845ad5d6558703d20567d8702155598325db8 (affected, git); ≥ 5fb9b459b3686e366640edd4e62805ef7b4de927; < 9911b1ed187a770a43950bf51f340ad4b7beecba (affected, git). Source: CNA: Linux
- Linux / Linux: 6.18 (affected); ≥ 0; < 6.18 (unaffected, semver); ≥ 6.18.11; ≤ 6.18.* (unaffected, semver); ≥ 6.19.1; ≤ 6.19.* (unaffected, semver); ≥ 7.0; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: 0.09% as of 2026-11-05; percentile 0.36%

- 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/f664e6e8a81103cb45c8802a9bc7499e0902c458 (CNA: Linux)

- https://git.kernel.org/stable/c/be8845ad5d6558703d20567d8702155598325db8 (CNA: Linux)

- https://git.kernel.org/stable/c/9911b1ed187a770a43950bf51f340ad4b7beecba (CNA: Linux)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-31535; retrieved 2026-11-05; source updated 2026-11-05

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-31535; retrieved 2026-11-05; source updated Not reported

Revision: fdd184063840a33869c3c5dbd46868cc1d73279da3443a9ba7c18d939cba390d

Canonical: https://y2.dev/cve/CVE-2026-31535

## 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.