CVE-2026-107937

Status: Undergoing AnalysisHigh (7.5)—

In Apache CXF, the parser for multipart/MTOM attachment part headers did not fully enforce the configured attachment-max-header-size (default 300 characters) and attachment-headers-max-count (default 500) limits. The size limit was applied only to each physical line, not to a header value built from continuation lines or to the combined values of a repeated header. The count limit was checked against the number of distinct header names, not the total number of header lines. A remote, unauthenticated attacker could send a multipart request with very large folded or repeated part headers. The server would then allocate memory without bound, causing a denial of service. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

CVSS

Version: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base score: 7.5

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.24%
Percentile among all scored CVEs: 14
Score date: 10/15/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

ExploitationT1190 Exploit Public-Facing Applicationinitial access92 %
Primary impactT1499 Endpoint Denial of Serviceimpact90 %

Vector AV:N/PR:N/UI:N y descripción: un atacante remoto no autenticado envía multipart con cabeceras excesivas y la memoria crece sin límite, causando DoS.

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Filter Network Traffic Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Application Isolation and Sandboxing

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Apache — CXF^AI

CWEs

CWE-770

References

Raw JSON (NVD)

Show

{
  "id": "CVE-2026-107937",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-107937",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-10-15T17:45:18.146774Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "security@apache.org",
      "affectedData": [
        {
          "vendor": "Apache Software Foundation",
          "product": "Apache CXF",
          "versions": [
            {
              "status": "affected",
              "version": "4.2.0",
              "lessThan": "4.2.4",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "4.0.0",
              "lessThan": "4.1.9",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "0",
              "lessThan": "3.6.13",
              "versionType": "semver"
            }
          ],
          "packageURL": "pkg:maven/org.apache.cxf/cxf-core",
          "packageName": "org.apache.cxf:cxf-core",
          "collectionURL": "https://repo.maven.apache.org/maven2",
          "defaultStatus": "unaffected"
        }
      ]
    }
  ],
  "published": "2026-10-09T11:17:02.107",
  "references": [
    {
      "url": "https://lists.apache.org/thread.html/x9twtpv3d04qj83t6w9xkh9y2q28zztj",
      "source": "security@apache.org"
    },
    {
      "url": "http://www.openwall.com/lists/oss-security/2026/10/09/12",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Undergoing Analysis",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "description": [
        {
          "lang": "en",
          "value": "CWE-770"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In Apache CXF, the parser for multipart/MTOM attachment part headers did not fully enforce the configured attachment-max-header-size (default 300 characters) and attachment-headers-max-count (default 500) limits. The size limit was applied only to each physical line, not to a header value built from continuation lines or to the combined values of a repeated header. The count limit was checked against the number of distinct header names, not the total number of header lines. A remote, unauthenticated attacker could send a multipart request with very large folded or repeated part headers. The server would then allocate memory without bound, causing a denial of service. \nUsers are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue."
    }
  ],
  "lastModified": "2026-10-15T18:17:24.767",
  "sourceIdentifier": "security@apache.org"
}