CVE-2026-98773 (GCVE-0-2026-98773)
Vulnerability from cvelistv5
Published
2026-10-18 15:48
Modified
2026-10-30 12:39
Severity ?
Summary
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.
References
Impacted products
Vendor Product Version
Linux Linux Version: d826061aa64cb28089bf4c73e301dd7928662b84
Version: 8fb82e3555a7d56a05d8ef0edee9859f889c0860
Version: 603d5a7110832e10165d21f9a1486399457177de
Version: 5d29d7ff8679e5a525f22da467ba33c042e8029b
Version: f58752ebcb35e156c85cd1a82d6579c7af3b9023
Version: f58752ebcb35e156c85cd1a82d6579c7af3b9023
Version: 283f8162cc3c82086537cbc7dc01870dbeb07a91
Version: f77f10bc76c2da86b4248269472f6d971e37828b
Version: 6.1.175   ≤
Version: 6.6.136   ≤
Version: 6.12.83   ≤
Version: 6.18.24   ≤
Version: 6.19.14   ≤
Version: 7.0.1   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/usb/class/cdc-acm.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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            {
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              "status": "affected",
              "version": "6.6.136",
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            },
            {
              "lessThan": "6.12.113",
              "status": "affected",
              "version": "6.12.83",
              "versionType": "semver"
            },
            {
              "lessThan": "6.18.56",
              "status": "affected",
              "version": "6.18.24",
              "versionType": "semver"
            },
            {
              "lessThan": "6.20",
              "status": "affected",
              "version": "6.19.14",
              "versionType": "semver"
            },
            {
              "lessThan": "7.1",
              "status": "affected",
              "version": "7.0.1",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/usb/class/cdc-acm.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "lessThan": "7.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.191",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.113",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.56",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.10",
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            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.191",
                  "versionStartIncluding": "6.1.175",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.160",
                  "versionStartIncluding": "6.6.136",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.56",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.10",
                  "versionStartIncluding": "7.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "7.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.19.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "7.0.1",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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-\u003edisconnected 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-\u003edisconnected 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-\u003euse = false and\nautopm counter) and does not touch the hardware path."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-30T12:39:41.890Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/d97da42e9de577dc827d4e8866e6971deefe2d9c"
        },
        {
          "url": "https://git.kernel.org/stable/c/d86775e79838d7d2e38ccf506a7d0f8e2dd4d5d0"
        },
        {
          "url": "https://git.kernel.org/stable/c/9742905d9ed5bf23ebe4c100dec80b6bc50fb522"
        },
        {
          "url": "https://git.kernel.org/stable/c/a0ed07b5bbb2d8fcef86810453216070691816e7"
        },
        {
          "url": "https://git.kernel.org/stable/c/420ca35af891d33522cc08504768ccd60a4c450a"
        },
        {
          "url": "https://git.kernel.org/stable/c/dc614d6bc991740d41d5a99ac7765c4b675dda88"
        }
      ],
      "title": "USB: cdc-acm: skip URB restart in port_shutdown if disconnected",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98773",
    "datePublished": "2026-10-18T15:48:09.093Z",
    "dateReserved": "2026-09-25T10:25:14.369Z",
    "dateUpdated": "2026-10-30T12:39:41.890Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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