# CVE-2026-64487: ALSA: caiaq: fix out-of-bounds read in the Traktor Kontrol S4 input parser

Status: published. Published: 2026-07-25. Updated: 2026-11-12.

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

ALSA: caiaq: fix out-of-bounds read in the Traktor Kontrol S4 input parser

snd_usb_caiaq_tks4_dispatch() decodes the Traktor Kontrol S4 input
stream in fixed 16-byte (TKS4_MSGBLOCK_SIZE) message blocks. On every
iteration it advances buf and subtracts the block size while looping on
"while (len)".

len is urb->actual_length. That value is supplied by the device and is
not guaranteed to be a multiple of 16. When a final short block leaves
len between 1 and 15, the loop runs once more, reads up to buf[15], and
then does "len -= TKS4_MSGBLOCK_SIZE". As len is unsigned this underflows
to a huge value. The loop then keeps iterating and walking buf far past
the end of the 512-byte ep4_in_buf, reading out of bounds until a bogus
block id happens to be hit.

Iterate only while a full message block is available. This stops the
unsigned underflow and silently drops any trailing partial block, which
carries no complete control value anyway.

The sibling endpoint-4 parsers are not affected. The Traktor Kontrol X1
and Maschine arms in snd_usb_caiaq_ep4_reply_dispatch() floor
urb->actual_length before dispatching.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/05df59b9a61f7ca66548df079d306c41da23845d
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/0680413f2f10aab43878dd3db711a6a9e45bab7c
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/3cad86197c7bf8b45bb1d8adc1099d0913e80469
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/70d6d4cfa4ad09688aed2ec8a0cfa72c31f60334
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/884f575cc6acb136eb4a161d925147f85b59c27e
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/a5fd3122283bf75c04f6414bf610100beb0565b0
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/de5f9edc705497b1b2c6b173b22f283486d2fd91
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/f7f3f9fd81e7adbaa12c2e62ee07f0e094a543fd

## Affected products and versions

- Linux / Linux: ≥ 15c5ab607045e278ebf4d2ca4aea2250617d50ca; < de5f9edc705497b1b2c6b173b22f283486d2fd91 (affected, git); ≥ 15c5ab607045e278ebf4d2ca4aea2250617d50ca; < 70d6d4cfa4ad09688aed2ec8a0cfa72c31f60334 (affected, git); ≥ 15c5ab607045e278ebf4d2ca4aea2250617d50ca; < 884f575cc6acb136eb4a161d925147f85b59c27e (affected, git); ≥ 15c5ab607045e278ebf4d2ca4aea2250617d50ca; < 05df59b9a61f7ca66548df079d306c41da23845d (affected, git); ≥ 15c5ab607045e278ebf4d2ca4aea2250617d50ca; < 3cad86197c7bf8b45bb1d8adc1099d0913e80469 (affected, git); ≥ 15c5ab607045e278ebf4d2ca4aea2250617d50ca; < a5fd3122283bf75c04f6414bf610100beb0565b0 (affected, git); ≥ 15c5ab607045e278ebf4d2ca4aea2250617d50ca; < 0680413f2f10aab43878dd3db711a6a9e45bab7c (affected, git); ≥ 15c5ab607045e278ebf4d2ca4aea2250617d50ca; < f7f3f9fd81e7adbaa12c2e62ee07f0e094a543fd (affected, git). Source: CNA: Linux
- Linux / Linux: 2.6.37 (affected); ≥ 0; < 2.6.37 (unaffected, semver); ≥ 5.10.261; ≤ 5.10.* (unaffected, semver); ≥ 5.15.212; ≤ 5.15.* (unaffected, semver); ≥ 6.1.178; ≤ 6.1.* (unaffected, semver); ≥ 6.6.145; ≤ 6.6.* (unaffected, semver); ≥ 6.12.96; ≤ 6.12.* (unaffected, semver); ≥ 6.18.39; ≤ 6.18.* (unaffected, semver); ≥ 7.1.4; ≤ 7.1.* (unaffected, semver); ≥ 7.2; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## NVD configuration conditions

Affected CPE matches depend on the following AND/OR and negation conditions:

```json
[
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "5.10.261",
            "versionStartIncluding": "2.6.37",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "5.15.212",
            "versionStartIncluding": "5.11",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "6.1.178",
            "versionStartIncluding": "5.16",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "6.6.145",
            "versionStartIncluding": "6.2",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "6.12.96",
            "versionStartIncluding": "6.7",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "6.18.39",
            "versionStartIncluding": "6.13",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "7.1.4",
            "versionStartIncluding": "6.19",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "OR"
  }
]
```

## Severity and prioritization

- CVSS 3.1: 7.1 (high); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H; source: NVD: nvd@nist.gov

- CISA KEV: No listing in collected sources

- EPSS: 0.18% as of 2026-11-10; percentile 8.11%

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

- Weaknesses: CWE-125

## Exploit evidence

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

## References

- https://git.kernel.org/stable/c/de5f9edc705497b1b2c6b173b22f283486d2fd91 (CNA: Linux)

- https://git.kernel.org/stable/c/70d6d4cfa4ad09688aed2ec8a0cfa72c31f60334 (CNA: Linux)

- https://git.kernel.org/stable/c/884f575cc6acb136eb4a161d925147f85b59c27e (CNA: Linux)

- https://git.kernel.org/stable/c/05df59b9a61f7ca66548df079d306c41da23845d (CNA: Linux)

- https://git.kernel.org/stable/c/3cad86197c7bf8b45bb1d8adc1099d0913e80469 (CNA: Linux)

- https://git.kernel.org/stable/c/a5fd3122283bf75c04f6414bf610100beb0565b0 (CNA: Linux)

- https://git.kernel.org/stable/c/0680413f2f10aab43878dd3db711a6a9e45bab7c (CNA: Linux)

- https://git.kernel.org/stable/c/f7f3f9fd81e7adbaa12c2e62ee07f0e094a543fd (CNA: Linux)

- https://git.kernel.org/stable/c/05df59b9a61f7ca66548df079d306c41da23845d (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

- https://git.kernel.org/stable/c/0680413f2f10aab43878dd3db711a6a9e45bab7c (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

- https://git.kernel.org/stable/c/3cad86197c7bf8b45bb1d8adc1099d0913e80469 (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

- https://git.kernel.org/stable/c/70d6d4cfa4ad09688aed2ec8a0cfa72c31f60334 (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

- https://git.kernel.org/stable/c/884f575cc6acb136eb4a161d925147f85b59c27e (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

- https://git.kernel.org/stable/c/a5fd3122283bf75c04f6414bf610100beb0565b0 (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

- https://git.kernel.org/stable/c/de5f9edc705497b1b2c6b173b22f283486d2fd91 (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

- https://git.kernel.org/stable/c/f7f3f9fd81e7adbaa12c2e62ee07f0e094a543fd (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-64487; retrieved 2026-11-06; source updated 2026-11-06

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64487; retrieved 2026-11-12; source updated 2026-11-12

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-64487; retrieved 2026-11-12; source updated Not reported

Revision: 6808d0d98bfcff4273354646daf54191f4f0f1f0a27b2315fc57251010ce3514

Canonical: https://y2.dev/cve/CVE-2026-64487

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