CVE-2026-33523 (GCVE-0-2026-33523)

Vulnerability from cvelistv5 – Published: 2026-05-04 14:40 – Updated: 2026-05-04 17:32
VLAI?
Title
Apache HTTP Server: multiple modules: HTTP response splitting forwarding malicious status line
Summary
HTTP response splitting vulnerability in multiple Apache HTTP Server modules with untrusted or compromised backend servers. This issue affects Apache HTTP Server: from through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.
Severity ?
No CVSS data available.
CWE
  • CWE-443 - HTTP response splitting
Assigner
References
Impacted products
Vendor Product Version
Apache Software Foundation Apache HTTP Server Affected: 2.4.0 , ≤ 2.4.66 (semver)
Create a notification for this product.
Credits
Haruki Oyama (Waseda University) Merih Mengisteab Dawit Jeong
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
              "baseScore": 6.5,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "LOW",
              "integrityImpact": "LOW",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-33523",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-04T15:55:00.471385Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-04T15:56:35.673Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "providerMetadata": {
          "dateUpdated": "2026-05-04T17:32:49.282Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "http://www.openwall.com/lists/oss-security/2026/05/04/23"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Apache HTTP Server",
          "vendor": "Apache Software Foundation",
          "versions": [
            {
              "lessThanOrEqual": "2.4.66",
              "status": "affected",
              "version": "2.4.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Haruki Oyama (Waseda University)"
        },
        {
          "lang": "en",
          "type": "finder",
          "value": "Merih Mengisteab"
        },
        {
          "lang": "en",
          "type": "finder",
          "value": "Dawit Jeong"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eHTTP response splitting vulnerability in multiple Apache HTTP Server modules with untrusted or compromised backend servers.\u003c/p\u003e\u003cp\u003eThis issue affects Apache HTTP Server: from through 2.4.66.\u003c/p\u003e\u003cp\u003eUsers are recommended to upgrade to version 2.4.67, which fixes the issue.\u003c/p\u003e"
            }
          ],
          "value": "HTTP response splitting vulnerability in multiple Apache HTTP Server modules with untrusted or compromised backend servers.\n\nThis issue affects Apache HTTP Server: from through 2.4.66.\n\nUsers are recommended to upgrade to version 2.4.67, which fixes the issue."
        }
      ],
      "metrics": [
        {
          "other": {
            "content": {
              "text": "low"
            },
            "type": "Textual description of severity"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-443",
              "description": "CWE-443: HTTP response splitting",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-04T14:40:41.430Z",
        "orgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
        "shortName": "apache"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://httpd.apache.org/security/vulnerabilities_24.html"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "timeline": [
        {
          "lang": "en",
          "time": "2026-03-05T12:00:00.000Z",
          "value": "reported"
        },
        {
          "lang": "eng",
          "time": "2026-05-04T12:00:00.000Z",
          "value": "2.4.67 released"
        },
        {
          "lang": "en",
          "time": "2026-05-04T12:00:00.000Z",
          "value": "fixed in 2.4.x by r1933360"
        }
      ],
      "title": "Apache HTTP Server: multiple modules: HTTP response splitting forwarding malicious status line",
      "x_generator": {
        "engine": "Vulnogram 0.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
    "assignerShortName": "apache",
    "cveId": "CVE-2026-33523",
    "datePublished": "2026-05-04T14:40:41.430Z",
    "dateReserved": "2026-03-20T17:29:39.696Z",
    "dateUpdated": "2026-05-04T17:32:49.282Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-33523\",\"sourceIdentifier\":\"security@apache.org\",\"published\":\"2026-05-04T15:16:04.227\",\"lastModified\":\"2026-05-04T17:16:23.060\",\"vulnStatus\":\"Undergoing Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"HTTP response splitting vulnerability in multiple Apache HTTP Server modules with untrusted or compromised backend servers.\\n\\nThis issue affects Apache HTTP Server: from through 2.4.66.\\n\\nUsers are recommended to upgrade to version 2.4.67, which fixes the issue.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N\",\"baseScore\":6.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"LOW\",\"integrityImpact\":\"LOW\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":3.9,\"impactScore\":2.5}]},\"weaknesses\":[{\"source\":\"security@apache.org\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-443\"}]}],\"references\":[{\"url\":\"https://httpd.apache.org/security/vulnerabilities_24.html\",\"source\":\"security@apache.org\"}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 6.5, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N\", \"integrityImpact\": \"LOW\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"NONE\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"LOW\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-33523\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-05-04T15:55:00.471385Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-05-04T15:55:21.968Z\"}}], \"cna\": {\"title\": \"Apache HTTP Server: multiple modules: HTTP response splitting forwarding malicious status line\", \"source\": {\"discovery\": \"UNKNOWN\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Haruki Oyama (Waseda University)\"}, {\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Merih Mengisteab\"}, {\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Dawit Jeong\"}], \"metrics\": [{\"other\": {\"type\": \"Textual description of severity\", \"content\": {\"text\": \"low\"}}}], \"affected\": [{\"vendor\": \"Apache Software Foundation\", \"product\": \"Apache HTTP Server\", \"versions\": [{\"status\": \"affected\", \"version\": \"2.4.0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"2.4.66\"}], \"defaultStatus\": \"unaffected\"}], \"timeline\": [{\"lang\": \"en\", \"time\": \"2026-03-05T12:00:00.000Z\", \"value\": \"reported\"}, {\"lang\": \"eng\", \"time\": \"2026-05-04T12:00:00.000Z\", \"value\": \"2.4.67 released\"}, {\"lang\": \"en\", \"time\": \"2026-05-04T12:00:00.000Z\", \"value\": \"fixed in 2.4.x by r1933360\"}], \"references\": [{\"url\": \"https://httpd.apache.org/security/vulnerabilities_24.html\", \"tags\": [\"vendor-advisory\"]}], \"x_generator\": {\"engine\": \"Vulnogram 0.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"HTTP response splitting vulnerability in multiple Apache HTTP Server modules with untrusted or compromised backend servers.\\n\\nThis issue affects Apache HTTP Server: from through 2.4.66.\\n\\nUsers are recommended to upgrade to version 2.4.67, which fixes the issue.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eHTTP response splitting vulnerability in multiple Apache HTTP Server modules with untrusted or compromised backend servers.\u003c/p\u003e\u003cp\u003eThis issue affects Apache HTTP Server: from through 2.4.66.\u003c/p\u003e\u003cp\u003eUsers are recommended to upgrade to version 2.4.67, which fixes the issue.\u003c/p\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-443\", \"description\": \"CWE-443: HTTP response splitting\"}]}], \"providerMetadata\": {\"orgId\": \"f0158376-9dc2-43b6-827c-5f631a4d8d09\", \"shortName\": \"apache\", \"dateUpdated\": \"2026-05-04T14:40:41.430Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-33523\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-05-04T15:56:35.673Z\", \"dateReserved\": \"2026-03-20T17:29:39.696Z\", \"assignerOrgId\": \"f0158376-9dc2-43b6-827c-5f631a4d8d09\", \"datePublished\": \"2026-05-04T14:40:41.430Z\", \"assignerShortName\": \"apache\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




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.

Sightings

Author Source Type Date Other

Nomenclature

  • 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.
  • 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.



Detection rules are retrieved from Rulezet.