CVE-2026-48986 (GCVE-0-2026-48986)

Vulnerability from cvelistv5 – Published: 2026-06-18 17:20 – Updated: 2026-06-18 17:20
VLAI
Title
pam_usb: Infinite loop DoS in process-tree walk when parent process exits during authentication
Summary
pam_usb provides hardware authentication for Linux using removable media. In pam_usb 0.9.1 and earlier, usb_get_process_parent_id() can cause an infinite loop DoS because it does not initialize *ppid on failure. In pusb_local_login(), the same variable is reused as input and output in a process-tree while loop; if /proc/<pid>/stat cannot be read (for example, when an ancestor process exits during authentication), the PID is not updated and the loop does not terminate. This hangs the authenticating process (such as sudo, sshd, or login) until it is forcibly terminated. This issue has been fixed in version 0.9.2.
Severity
4.7 (Medium)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE
  • CWE-835 - Loop with Unreachable Exit Condition ('Infinite Loop')
Assigner
References
Impacted products
Vendor Product Version
mcdope pam_usb Affected: < 0.9.2
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "pam_usb",
          "vendor": "mcdope",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.9.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "pam_usb provides hardware authentication for Linux using removable media. In pam_usb 0.9.1 and earlier, usb_get_process_parent_id() can cause an infinite loop DoS because it does not initialize *ppid on failure. In pusb_local_login(), the same variable is reused as input and output in a process-tree while loop; if /proc/\u003cpid\u003e/stat cannot be read (for example, when an ancestor process exits during authentication), the PID is not updated and the loop does not terminate. This hangs the authenticating process (such as sudo, sshd, or login) until it is forcibly terminated. This issue has been fixed in version 0.9.2."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 4.7,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-835",
              "description": "CWE-835: Loop with Unreachable Exit Condition (\u0027Infinite Loop\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-18T17:20:51.643Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/mcdope/pam_usb/security/advisories/GHSA-h28h-9hc3-v595",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/mcdope/pam_usb/security/advisories/GHSA-h28h-9hc3-v595"
        },
        {
          "name": "https://github.com/mcdope/pam_usb/releases/tag/0.9.2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/mcdope/pam_usb/releases/tag/0.9.2"
        }
      ],
      "source": {
        "advisory": "GHSA-h28h-9hc3-v595",
        "discovery": "UNKNOWN"
      },
      "title": "pam_usb: Infinite loop DoS in process-tree walk when parent process exits during authentication"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-48986",
    "datePublished": "2026-06-18T17:20:51.643Z",
    "dateReserved": "2026-05-26T23:26:07.975Z",
    "dateUpdated": "2026-06-18T17:20:51.643Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-48986",
      "date": "2026-06-14",
      "epss": "0.00014",
      "percentile": "0.02857"
    }
  }
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • 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.
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