FKIE_CVE-2026-9256

Vulnerability from fkie_nvd - Published: 2026-05-22 15:16 - Updated: 2026-06-18 06:16
Severity
8.1 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that references multiple such captures (for example, $1$2) in a redirect or arguments context. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
References
f5sirt@f5.comhttps://my.f5.com/manage/s/article/K000161377Mitigation, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108http://www.openwall.com/lists/oss-security/2026/05/22/14Mailing List, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2026/06/msg00023.html
Impacted products
Vendor Product Version
f5 nginx_open_source *
f5 nginx_open_source *
f5 nginx_open_source 1.31.0
f5 nginx_plus *
f5 nginx_plus *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unknown",
          "modules": [
            "ngx_http_rewrite_module"
          ],
          "product": "NGINX Plus",
          "vendor": "F5",
          "versions": [
            {
              "lessThan": "37.0.1.1",
              "status": "affected",
              "version": "37.0",
              "versionType": "custom"
            },
            {
              "lessThan": "R36 P5",
              "status": "affected",
              "version": "R36",
              "versionType": "custom"
            },
            {
              "lessThan": "R32 P7",
              "status": "affected",
              "version": "R32",
              "versionType": "custom"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "modules": [
            "ngx_http_rewrite_module"
          ],
          "product": "NGINX Open Source",
          "vendor": "F5",
          "versions": [
            {
              "lessThan": "1.31.1",
              "status": "affected",
              "version": "1.31.0",
              "versionType": "custom"
            },
            {
              "lessThan": "1.30.2",
              "status": "affected",
              "version": "1.30.0",
              "versionType": "custom"
            },
            {
              "lessThanOrEqual": "0.9.7",
              "status": "affected",
              "version": "0.1.17",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "f5sirt@f5.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "634D5CE2-039A-4D93-A03D-0FD7D0DEF686",
              "versionEndIncluding": "0.9.7",
              "versionStartIncluding": "0.1.17",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "256A7426-EE20-42E5-B4C9-974EE51E374F",
              "versionEndIncluding": "1.30.1",
              "versionStartIncluding": "1.0.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:f5:nginx_open_source:1.31.0:*:*:*:*:*:*:*",
              "matchCriteriaId": "A33B307E-A953-42D8-9ED6-975AA79C160F",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "A3674D49-0D63-4E56-A912-E887F722DDAF",
              "versionEndExcluding": "37.0.1.1",
              "versionStartIncluding": "37.0.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "0B153576-468F-48C2-9BC8-922A938AB235",
              "versionEndIncluding": "r36",
              "versionStartIncluding": "r32",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that references multiple such captures (for example, $1$2) in a redirect or arguments context. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. \n\n\nNote: Software versions which have reached End of Technical Support (EoTS) are not evaluated."
    }
  ],
  "id": "CVE-2026-9256",
  "lastModified": "2026-06-18T06:16:58.190",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 5.9,
        "source": "f5sirt@f5.com",
        "type": "Secondary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "HIGH",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 9.2,
          "baseSeverity": "CRITICAL",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "f5sirt@f5.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-9256",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-05-22T00:00:00+00:00",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-05-22T15:16:27.073",
  "references": [
    {
      "source": "f5sirt@f5.com",
      "tags": [
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://my.f5.com/manage/s/article/K000161377"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "url": "http://www.openwall.com/lists/oss-security/2026/05/22/14"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://lists.debian.org/debian-lts-announce/2026/06/msg00023.html"
    }
  ],
  "sourceIdentifier": "f5sirt@f5.com",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-122"
        }
      ],
      "source": "f5sirt@f5.com",
      "type": "Secondary"
    }
  ]
}


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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.
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