CVE-2026-98773

Full vulnerability record from the local CVENow database.

Description

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.

Severity

Not scored

CVSS score

Not available

Vulnerability status

Received

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-10-18 16:17:31.223000

Last modified

2026-10-30 13:21:27.007000

View original CVE JSON

{
  "id": "CVE-2026-98773",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-10-18T16:17:31.223",
  "lastModified": "2026-10-30T13:21:27.007",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nUSB: cdc-acm: skip URB restart in port_shutdown if disconnected\n\nacm_port_shutdown() is called from the tty-port machinery whenever the\nlast user closes the port.  acm_disconnect() sets acm->disconnected and\ncalls tty_port_tty_vhangup(), which eventually triggers port_shutdown().\nAt that point acm_disconnect() has already called acm_poison_urbs() and\nis about to free the control and read URBs.\n\nHowever, acm_port_shutdown() unconditionally calls acm_unpoison_urbs()\nand, when the ALWAYS_POLL_CTRL quirk is set, immediately re-submits the\nctrlurb and all read URBs.  If the concurrent acm_disconnect() then\nfrees those URBs and their DMA buffers while they are in-flight, the\nresult is a use-after-free in acm_ctrl_irq() or acm_read_bulk_callback()\naccessing the freed DMA memory.\n\nFix by checking acm->disconnected after draining the delayed anchor and\nreturning early: if we are in a disconnect path the URBs must remain\npoisoned and must not be resubmitted.\n\nThe early return is placed after the delayed-anchor drain loop because\nthat loop only cancels write-side accounting (wb->use = false and\nautopm counter) and does not touch the hardware path."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "drivers/usb/class/cdc-acm.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "d826061aa64cb28089bf4c73e301dd7928662b84",
              "lessThan": "d97da42e9de577dc827d4e8866e6971deefe2d9c",
              "versionType": "git",
              "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": "283f8162cc3c82086537cbc7dc01870dbeb07a91",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "f77f10bc76c2da86b4248269472f6d971e37828b",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "6.1.175",
              "lessThan": "6.1.191",
              "versionType": "semver",
              "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": "6.19.14",
              "lessThan": "6.20",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "7.0.1",
              "lessThan": "7.1",
              "versionType": "semver",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "drivers/usb/class/cdc-acm.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "7.1",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "7.1",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.191",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.160",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.113",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.56",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2.10",
              "lessThanOrEqual": "7.2.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.3",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {},
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/420ca35af891d33522cc08504768ccd60a4c450a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/9742905d9ed5bf23ebe4c100dec80b6bc50fb522",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/a0ed07b5bbb2d8fcef86810453216070691816e7",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/d86775e79838d7d2e38ccf506a7d0f8e2dd4d5d0",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/d97da42e9de577dc827d4e8866e6971deefe2d9c",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/dc614d6bc991740d41d5a99ac7765c4b675dda88",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}