CVE-2026-98773 (GCVE-0-2026-98773)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:48 – Updated: 2026-10-30 12:39
VLAI
Title
USB: cdc-acm: skip URB restart in port_shutdown if disconnected
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.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6820 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: d826061aa64cb28089bf4c73e301dd7928662b84 , < d97da42e9de577dc827d4e8866e6971deefe2d9c (git)
Affected: 8fb82e3555a7d56a05d8ef0edee9859f889c0860 , < d86775e79838d7d2e38ccf506a7d0f8e2dd4d5d0 (git)
Affected: 603d5a7110832e10165d21f9a1486399457177de , < 9742905d9ed5bf23ebe4c100dec80b6bc50fb522 (git)
Affected: 5d29d7ff8679e5a525f22da467ba33c042e8029b , < a0ed07b5bbb2d8fcef86810453216070691816e7 (git)
Affected: f58752ebcb35e156c85cd1a82d6579c7af3b9023 , < 420ca35af891d33522cc08504768ccd60a4c450a (git)
Affected: f58752ebcb35e156c85cd1a82d6579c7af3b9023 , < dc614d6bc991740d41d5a99ac7765c4b675dda88 (git)
Affected: 283f8162cc3c82086537cbc7dc01870dbeb07a91 (git)
Affected: f77f10bc76c2da86b4248269472f6d971e37828b (git)
Affected: 6.1.175 , < 6.1.191 (semver)
Affected: 6.6.136 , < 6.6.160 (semver)
Affected: 6.12.83 , < 6.12.113 (semver)
Affected: 6.18.24 , < 6.18.56 (semver)
Affected: 6.19.14 , < 6.20 (semver)
Affected: 7.0.1 , < 7.1 (semver)
guessed Create a notification for this product.
Linux Linux Affected: 7.1
Unaffected: 0 , < 7.1 (semver)
Unaffected: 6.1.191 , ≤ 6.1.* (semver)
Unaffected: 6.6.160 , ≤ 6.6.* (semver)
Unaffected: 6.12.113 , ≤ 6.12.* (semver)
Unaffected: 6.18.56 , ≤ 6.18.* (semver)
Unaffected: 7.2.10 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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{
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          "product": "Linux",
          "programFiles": [
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              "version": "7.3",
              "versionType": "original_commit_for_fix"
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          ]
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      ],
      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
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      "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": [
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          "url": "https://git.kernel.org/stable/c/d97da42e9de577dc827d4e8866e6971deefe2d9c"
        },
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          "url": "https://git.kernel.org/stable/c/d86775e79838d7d2e38ccf506a7d0f8e2dd4d5d0"
        },
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        },
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          "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"
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  "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",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-98773",
      "date": "2026-11-02",
      "epss": "0.00172",
      "percentile": "0.06608"
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    "microsoft_vex": {
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      "cve": "CVE-2026-98773",
      "id": "msrc_CVE-2026-98773",
      "initial_release_date": "2026-10-20T01:08:07.000Z",
      "product_status:fixed": "1",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "USB: cdc-acm: skip URB restart in port_shutdown if disconnected",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98773.json",
      "version": "3"
    },
    "nvd": {
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                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "drivers/usb/class/cdc-acm.c"
                ],
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "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-\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."
          }
        ],
        "id": "CVE-2026-98773",
        "lastModified": "2026-10-30T13:21:27.007",
        "metrics": {},
        "published": "2026-10-18T16:17:31.223",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          },
          {
            "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"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-10-23T08:07:15+00:00",
      "cve": "CVE-2026-98773",
      "id": "CVE-2026-98773",
      "initial_release_date": "2026-10-18T00:00:00+00:00",
      "product_status:known_affected": "14",
      "product_status:known_not_affected": "264",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: USB: cdc-acm: skip URB restart in port_shutdown if disconnected",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98773.json",
      "version": "3"
    }
  }
}



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  • 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.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.