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USB: cdc-acm: skip URB restart in port_shutdown if disconnected

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: USB: cdc-acm: skip URB restart in port_shutdown if disconnected acm_port_shutdown() is called from the tty-port machinery whenever the last user closes the port. acm_disconnect() sets acm->disconnected and calls tty_port_tty_vhangup(), which eventually triggers port_shutdown(). At that point acm_disconnect() has already called acm_poison_urbs() and is about to free the control and read URBs. However, acm_port_shutdown() unconditionally calls acm_unpoison_urbs() and, when the ALWAYS_POLL_CTRL quirk is set, immediately re-submits the ctrlurb and all read URBs. If the concurrent acm_disconnect() then frees those URBs and their DMA buffers while they are in-flight, the result is a use-after-free in acm_ctrl_irq() or acm_read_bulk_callback() accessing the freed DMA memory. Fix by checking acm->disconnected after draining the delayed anchor and returning early: if we are in a disconnect path the URBs must remain poisoned and must not be resubmitted. The early return is placed after the delayed-anchor drain loop because that loop only cancels write-side accounting (wb->use = false and autopm counter) and does not touch the hardware path.

Announced Source revision 1
Original source ↗

CVE-2026-98773

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-98773

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "8fb82e3555a7d56a05d8ef0edee9859f889c0860",
        "lessThan": "d86775e79838d7d2e38ccf506a7d0f8e2dd4d5d0",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "603d5a7110832e10165d21f9a1486399457177de",
        "lessThan": "9742905d9ed5bf23ebe4c100dec80b6bc50fb522",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "5d29d7ff8679e5a525f22da467ba33c042e8029b",
        "lessThan": "a0ed07b5bbb2d8fcef86810453216070691816e7",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "f58752ebcb35e156c85cd1a82d6579c7af3b9023",
        "lessThan": "420ca35af891d33522cc08504768ccd60a4c450a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "f58752ebcb35e156c85cd1a82d6579c7af3b9023",
        "lessThan": "dc614d6bc991740d41d5a99ac7765c4b675dda88",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "d826061aa64cb28089bf4c73e301dd7928662b84",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "283f8162cc3c82086537cbc7dc01870dbeb07a91",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "f77f10bc76c2da86b4248269472f6d971e37828b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6.6.136",
        "lessThan": "6.6.160",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "6.12.83",
        "lessThan": "6.12.113",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "6.18.24",
        "lessThan": "6.18.56",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "6.1.175",
        "lessThan": "6.2",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "6.19.14",
        "lessThan": "6.20",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "7.0.1",
        "lessThan": "7.1",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "drivers/usb/class/cdc-acm.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "7.1"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "7.1",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.113",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.56",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.10",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/usb/class/cdc-acm.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-98773

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#48969 · Revision 1
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