Vulnerability-Lookup

GHSA-HJW3-QCFV-9G4P

Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32

Details

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

usb: gadget: u_audio: Fix use-after-free on sound card disconnect

g_audio_cleanup() invokes snd_card_free_when_closed() to initiate sound card teardown and immediately frees the underlying struct snd_uac_chip context. However, snd_card_free_when_closed() returns asynchronously while ALSA control elements (kctls) remain open in userspace.

When userspace control applications access or close these open file descriptors, kctl callbacks attempt to dereference kctl->private_data pointing to &uac->c_prm or &uac->p_prm within the freed uac structure, resulting in a use-after-free (UAF) memory corruption.

Fix this issue by deferring the destruction of struct snd_uac_chip until all references to the ALSA sound card are released. Register a custom card->private_free callback (u_audio_card_free) during g_audio_setup() that frees uac and its associated playback/capture request and ring buffers only when the sound card reference count drops to zero.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-89736"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-11T20:20:04Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: u_audio: Fix use-after-free on sound card disconnect\n\ng_audio_cleanup() invokes snd_card_free_when_closed() to initiate sound\ncard teardown and immediately frees the underlying struct snd_uac_chip\ncontext. However, snd_card_free_when_closed() returns asynchronously\nwhile ALSA control elements (kctls) remain open in userspace.\n\nWhen userspace control applications access or close these open file\ndescriptors, kctl callbacks attempt to dereference kctl-\u003eprivate_data\npointing to \u0026uac-\u003ec_prm or \u0026uac-\u003ep_prm within the freed uac structure,\nresulting in a use-after-free (UAF) memory corruption.\n\nFix this issue by deferring the destruction of struct snd_uac_chip until\nall references to the ALSA sound card are released. Register a custom\ncard-\u003eprivate_free callback (u_audio_card_free) during g_audio_setup()\nthat frees uac and its associated playback/capture request and ring\nbuffers only when the sound card reference count drops to zero.",
  "id": "GHSA-hjw3-qcfv-9g4p",
  "modified": "2026-09-14T15:32:35Z",
  "published": "2026-09-11T21:31:38Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89736"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4e747c864a88537e18b1ffc19a1954c9686bb8e1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6f46762196f04464e1050a9ee94e72b917db9010"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/79a92896e2bb9471550c56fc23d8d93592f04c27"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/858965947081d10d41d9a1010a540d3d5eea958b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/891a8d11f4d5eb50b2ce7570f4f98204a7a57493"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a7ecd1a04f4f485d7be6443d0f0b2c61a800cb82"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c74ff0b1a0fca53d3ac185873c87d6a719b30a47"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f983793f03148b097977f200298db215cd2d4438"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-89736 (GCVE-0-2026-89736)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:46 – Updated: 2026-09-14 12:02

Title

usb: gadget: u_audio: Fix use-after-free on sound card disconnect

Summary

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: u_audio: Fix use-after-free on sound card disconnect g_audio_cleanup() invokes snd_card_free_when_closed() to initiate sound card teardown and immediately frees the underlying struct snd_uac_chip context. However, snd_card_free_when_closed() returns asynchronously while ALSA control elements (kctls) remain open in userspace. When userspace control applications access or close these open file descriptors, kctl callbacks attempt to dereference kctl->private_data pointing to &uac->c_prm or &uac->p_prm within the freed uac structure, resulting in a use-after-free (UAF) memory corruption. Fix this issue by deferring the destruction of struct snd_uac_chip until all references to the ALSA sound card are released. Register a custom card->private_free callback (u_audio_card_free) during g_audio_setup() that frees uac and its associated playback/capture request and ring buffers only when the sound card reference count drops to zero.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

8 references

URL	Tags
https://git.kernel.org/stable/c/a7ecd1a04f4f485d7…
https://git.kernel.org/stable/c/f983793f03148b097…
https://git.kernel.org/stable/c/6f46762196f04464e…
https://git.kernel.org/stable/c/891a8d11f4d5eb50b…
https://git.kernel.org/stable/c/c74ff0b1a0fca53d3…
https://git.kernel.org/stable/c/4e747c864a88537e1…
https://git.kernel.org/stable/c/79a92896e2bb94715…
https://git.kernel.org/stable/c/858965947081d10d4…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 33f341c1fc60e172a3515c51bdabee11e83d1ee9 , < a7ecd1a04f4f485d7be6443d0f0b2c61a800cb82 (git) Affected: b131989797f7287d7fdadb2bababc05a15d44750 , < f983793f03148b097977f200298db215cd2d4438 (git) Affected: 3bc7324e4911351e39c54a62e6ca46321cb10faf , < 6f46762196f04464e1050a9ee94e72b917db9010 (git) Affected: 6c67ed9ad9b83e453e808f9b31a931a20a25629b , < 891a8d11f4d5eb50b2ce7570f4f98204a7a57493 (git) Affected: 6c67ed9ad9b83e453e808f9b31a931a20a25629b , < c74ff0b1a0fca53d3ac185873c87d6a719b30a47 (git) Affected: 6c67ed9ad9b83e453e808f9b31a931a20a25629b , < 4e747c864a88537e18b1ffc19a1954c9686bb8e1 (git) Affected: 6c67ed9ad9b83e453e808f9b31a931a20a25629b , < 79a92896e2bb9471550c56fc23d8d93592f04c27 (git) Affected: 6c67ed9ad9b83e453e808f9b31a931a20a25629b , < 858965947081d10d41d9a1010a540d3d5eea958b (git) Affected: 3e016ef2e72da93a2ea7afbb45de1b481b44d761 (git) Affected: 3256e152b645fc1e788ba44c2d8ced690113e3e6 (git) Affected: 0eda2004f38d95ef5715d62be884cd344260535b (git) Affected: 43ca70753dfffd517d2af126da28690f8f615605 (git) Affected: 5.10.177 , < 5.10.270 (semver) Affected: 5.15.105 , < 5.15.221 (semver) Affected: 6.1.22 , < 6.1.188 (semver) Affected: 4.14.312 , < 4.15 (semver) Affected: 4.19.280 , < 4.20 (semver) Affected: 5.4.240 , < 5.5 (semver) Affected: 6.2.9 , < 6.3 (semver)
Linux	Linux	Affected: 6.3 Unaffected: 0 , < 6.3 (semver) Unaffected: 5.10.270 , ≤ 5.10.* (semver) Unaffected: 5.15.221 , ≤ 5.15.* (semver) Unaffected: 6.1.188 , ≤ 6.1.* (semver) Unaffected: 6.6.157 , ≤ 6.6.* (semver) Unaffected: 6.12.109 , ≤ 6.12.* (semver) Unaffected: 6.18.50 , ≤ 6.18.* (semver) Unaffected: 7.2.4 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

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          "programFiles": [
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          ],
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              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
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              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
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            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
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            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: u_audio: Fix use-after-free on sound card disconnect\n\ng_audio_cleanup() invokes snd_card_free_when_closed() to initiate sound\ncard teardown and immediately frees the underlying struct snd_uac_chip\ncontext. However, snd_card_free_when_closed() returns asynchronously\nwhile ALSA control elements (kctls) remain open in userspace.\n\nWhen userspace control applications access or close these open file\ndescriptors, kctl callbacks attempt to dereference kctl-\u003eprivate_data\npointing to \u0026uac-\u003ec_prm or \u0026uac-\u003ep_prm within the freed uac structure,\nresulting in a use-after-free (UAF) memory corruption.\n\nFix this issue by deferring the destruction of struct snd_uac_chip until\nall references to the ALSA sound card are released. Register a custom\ncard-\u003eprivate_free callback (u_audio_card_free) during g_audio_setup()\nthat frees uac and its associated playback/capture request and ring\nbuffers only when the sound card reference count drops to zero."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The UAF is reached from local userspace: configfs UDC unbind calls afunc_unbind/f_audio_unbind \u2192 g_audio_cleanup, which frees snd_uac_chip while ALSA kctl/PCM fds still reference it; g_audio_setup runs at function bind with no USB host required, matching gadget teardown scores such as CVE-2024-38628.\nAC:L - The attacker controls both sides by issuing SNDRV_CTL_IOCTL_ELEM_READ/WRITE on the UAC mixer kctls while concurrently unbinding the gadget; snd_card_disconnect does not drain in-flight ioctls before g_audio_cleanup kfree()s the chip, so kctl get/put callbacks dereference freed uac_rtd_params and the race is freely retryable.\nPR:L - Android and embedded USB gadget HALs commonly delegate /sys/kernel/config/usb_gadget UDC writes to non-root service accounts, and the UAC gadget\u0027s ALSA control/PCM nodes are reachable by unprivileged local users; init-namespace root is not required once the gadget is deployed.\nUI:N - The attacker performs gadget unbind, holds ALSA fds, and issues mixer ioctls itself; no separate victim action such as plugging a cable or mounting a filesystem is required.\nS:U - The use-after-free corrupts kernel heap objects (snd_uac_chip and its playback/capture rings) within the same host kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - Kctl get/info/tlv callbacks (u_audio_volume_get, u_audio_rate_get, u_audio_volume_tlv) read volume, rate, and TLV fields from the already-freed snd_uac_chip and copy them to userspace, yielding a use-after-free disclosure primitive that kernel scoring treats as High confidentiality.\nI:H - Kctl put callbacks (u_audio_volume_put, u_audio_mute_put, u_audio_pitch_put) take prm-\u003elock and write volume/mute/pitch into the kfree()\u0027d snd_uac_chip, providing a write-after-free primitive that can be turned into arbitrary write or control-flow hijack.\nA:H - Use of the freed snd_uac_chip, including spin_lock_irqsave on prm-\u003elock and USB ISO completions with req-\u003econtext pointing into the freed object, reliably produces KASAN reports, oops, and kernel panic."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-14T12:02:23.539Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a7ecd1a04f4f485d7be6443d0f0b2c61a800cb82"
        },
        {
          "url": "https://git.kernel.org/stable/c/f983793f03148b097977f200298db215cd2d4438"
        },
        {
          "url": "https://git.kernel.org/stable/c/6f46762196f04464e1050a9ee94e72b917db9010"
        },
        {
          "url": "https://git.kernel.org/stable/c/891a8d11f4d5eb50b2ce7570f4f98204a7a57493"
        },
        {
          "url": "https://git.kernel.org/stable/c/c74ff0b1a0fca53d3ac185873c87d6a719b30a47"
        },
        {
          "url": "https://git.kernel.org/stable/c/4e747c864a88537e18b1ffc19a1954c9686bb8e1"
        },
        {
          "url": "https://git.kernel.org/stable/c/79a92896e2bb9471550c56fc23d8d93592f04c27"
        },
        {
          "url": "https://git.kernel.org/stable/c/858965947081d10d41d9a1010a540d3d5eea958b"
        }
      ],
      "title": "usb: gadget: u_audio: Fix use-after-free on sound card disconnect",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89736",
    "datePublished": "2026-09-11T19:46:44.608Z",
    "dateReserved": "2026-09-11T19:38:34.761Z",
    "dateUpdated": "2026-09-14T12:02:23.539Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

GHSA-HJW3-QCFV-9G4P

CVE-2026-89736 (GCVE-0-2026-89736)

Tags

Sightings

Nomenclature