FKIE_CVE-2026-105244

Vulnerability from fkie_nvd - Published: 2026-10-06 20:17 - Updated: 2026-10-07 15:17
Severity
5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Summary
Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net. Every character outside visible ASCII and space was removed from the record instead of being escaped, so non-ASCII text and control characters such as tabs disappeared without notice. A party whose data reaches a log message could make a distinct value look identical in the record, for example a user name holding a zero-width space logged as admin. Only applications that use RemoteSyslogAppender are affected. This issue affects Apache log4net: from 1.2.12 before 3.5.0. Users are recommended to upgrade to version 3.5.0, which fixes the issue.
References
security@apache.orghttps://github.com/apache/logging-log4net/commit/77717061b20d4346b6c0ce6b54643d85fb348bc7
security@apache.orghttps://github.com/apache/logging-log4net/pull/315
security@apache.orghttps://lists.apache.org/thread.html/q7649hhdodthoqw8jsjgtnb4m8qfy6d6
af854a3a-2127-422b-91ae-364da2661108http://www.openwall.com/lists/oss-security/2026/10/07/19
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://nuget.org/packages",
          "defaultStatus": "unaffected",
          "packageName": "log4net",
          "packageURL": "pkg:nuget/log4net",
          "product": "Apache log4net",
          "vendor": "Apache Software Foundation",
          "versions": [
            {
              "lessThan": "3.5.0",
              "status": "affected",
              "version": "1.2.12",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://nuget.org/packages",
          "defaultStatus": "unaffected",
          "packageName": "log4net",
          "packageURL": "pkg:nuget/log4net",
          "product": "Apache log4net",
          "repo": "https://gitbox.apache.org/repos/asf/logging-log4net.git",
          "vendor": "Apache Software Foundation",
          "versions": [
            {
              "lessThan": "77717061b20d4346b6c0ce6b54643d85fb348bc7",
              "status": "affected",
              "version": "56a2e146e21ff4737e1ff3ec308810e667873947",
              "versionType": "git"
            }
          ]
        }
      ],
      "source": "security@apache.org"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net.\n\nEvery character outside visible ASCII and space was removed from the record instead of being escaped, so non-ASCII text and control characters such as tabs disappeared without notice. A party whose data reaches a log message could make a distinct value look identical in the record, for example a user name holding a zero-width space logged as admin. Only applications that use RemoteSyslogAppender are affected.\n\nThis issue affects Apache log4net: from 1.2.12 before 3.5.0.\n\nUsers are recommended to upgrade to version 3.5.0, which fixes the issue."
    }
  ],
  "id": "CVE-2026-105244",
  "lastModified": "2026-10-07T15:17:07.430",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4,
        "source": "security@apache.org",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-105244",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-07T14:50:00.691563Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-10-06T20:17:16.297",
  "references": [
    {
      "source": "security@apache.org",
      "url": "https://github.com/apache/logging-log4net/commit/77717061b20d4346b6c0ce6b54643d85fb348bc7"
    },
    {
      "source": "security@apache.org",
      "url": "https://github.com/apache/logging-log4net/pull/315"
    },
    {
      "source": "security@apache.org",
      "url": "https://lists.apache.org/thread.html/q7649hhdodthoqw8jsjgtnb4m8qfy6d6"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "http://www.openwall.com/lists/oss-security/2026/10/07/19"
    }
  ],
  "sourceIdentifier": "security@apache.org",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-116"
        }
      ],
      "source": "security@apache.org",
      "type": "Secondary"
    }
  ]
}



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