CVE-2026-40701 (GCVE-0-2026-40701)

Vulnerability from cvelistv5 – Published: 2026-05-13 14:12 – Updated: 2026-05-13 16:07
VLAI
Title
NGINX ngx_http_ssl_module vulnerability
Summary
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssl_module module when the ssl_verify_client directive is set to "on" or "optional," and the ssl_ocsp directive is set to "on" or the leaf parameters are configured with a resolver. With this configuration, an unauthenticated attacker can send requests along with conditions beyond its control that may cause a heap-use-after-free error in the NGINX worker process. This vulnerability may result in limited modification of data or the NGINX worker process restarting.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Severity
4.8 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
6.3 (Medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-05-13 15:55 UTC
CWE
Assigner
References
URL Tags
https://my.f5.com/manage/s/article/K000161021 vendor-advisorypatch
Impacted products
Vendor Product Version CPE status
F5 NGINX Plus Unaffected: R37 , < * (custom)
Affected: R36 , < R36 P4 (custom)
Affected: R32 , < R32 P6 (custom)
guessed Create a notification for this product.
F5 NGINX Open Source Unaffected: 1.31.0 , < * (semver)
Affected: 1.19.0 , < 1.30.1 (semver)
guessed Create a notification for this product.
Date Public
2026-05-13 14:00
Credits
F5 acknowledges Zhenpeng (Leo) Lin of depthfirst for bringing this issue to our attention and following the highest standards of coordinated disclosure.
Show details on NVD website
To clipboard 

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              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "defaultStatus": "unknown",
              "modules": [
                "ngx_http_ssl_module"
              ],
              "product": "NGINX Plus",
              "vendor": "F5",
              "versions": [
                {
                  "lessThan": "*",
                  "status": "unaffected",
                  "version": "R37",
                  "versionType": "custom"
                },
                {
                  "lessThan": "R36 P4",
                  "status": "affected",
                  "version": "R36",
                  "versionType": "custom"
                },
                {
                  "lessThan": "R32 P6",
                  "status": "affected",
                  "version": "R32",
                  "versionType": "custom"
                }
              ]
            },
            {
              "defaultStatus": "unaffected",
              "modules": [
                "ngx_http_ssl_module"
              ],
              "product": "NGINX Open Source",
              "vendor": "F5",
              "versions": [
                {
                  "lessThan": "*",
                  "status": "unaffected",
                  "version": "1.31.0",
                  "versionType": "semver"
                },
                {
                  "lessThan": "1.30.1",
                  "status": "affected",
                  "version": "1.19.0",
                  "versionType": "semver"
                }
              ]
            }
          ],
          "credits": [
            {
              "lang": "en",
              "type": "finder",
              "value": "F5 acknowledges Zhenpeng (Leo) Lin of depthfirst for bringing this issue to our attention and following the highest standards of coordinated disclosure."
            }
          ],
          "datePublic": "2026-05-13T14:00:00.000Z",
          "descriptions": [
            {
              "lang": "en",
              "supportingMedia": [
                {
                  "base64": false,
                  "type": "text/html",
                  "value": "\u003cspan style=\"background-color: rgb(255, 255, 255);\"\u003e\n\n\u003cspan style=\"background-color: rgb(255, 255, 255);\"\u003eNGINX Plus and NGINX Open Source have a vulnerability in the \u003c/span\u003e\u003cstrong\u003engx_http_ssl_module\u003c/strong\u003e\u003cspan style=\"background-color: rgb(255, 255, 255);\"\u003e\u0026nbsp;module when the \u003c/span\u003e\u003cstrong\u003essl_verify_client\u003c/strong\u003e\u003cspan style=\"background-color: rgb(255, 255, 255);\"\u003e\u0026nbsp;directive is set to \"on\" or \"optional,\" and the \u003c/span\u003e\u003cstrong\u003essl_ocsp\u003c/strong\u003e\u003cspan style=\"background-color: rgb(255, 255, 255);\"\u003e\u0026nbsp;directive is set to \"on\" or the \u003c/span\u003e\u003cstrong\u003eleaf\u003c/strong\u003e\u003cspan style=\"background-color: rgb(255, 255, 255);\"\u003e\u0026nbsp;parameters are configured with a resolver. With this configuration, an unauthenticated attacker can send requests along with conditions beyond its control that may cause a heap-use-after-free error in the NGINX worker process. This vulnerability may result in limited modification of data or the NGINX worker process restarting.\u003c/span\u003e\n\n\u003c/span\u003e\n\n\u0026nbsp;Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated."
                }
              ],
              "value": "NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssl_module\u00a0module when the ssl_verify_client\u00a0directive is set to \"on\" or \"optional,\" and the ssl_ocsp\u00a0directive is set to \"on\" or the leaf\u00a0parameters are configured with a resolver. With this configuration, an unauthenticated attacker can send requests along with conditions beyond its control that may cause a heap-use-after-free error in the NGINX worker process. This vulnerability may result in limited modification of data or the NGINX worker process restarting.\n\n\n\n\u00a0Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated."
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "attackComplexity": "HIGH",
                "attackVector": "NETWORK",
                "availabilityImpact": "LOW",
                "baseScore": 4.8,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "LOW",
                "integrityImpact": "NONE",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L",
                "version": "3.1"
              },
              "format": "CVSS",
              "scenarios": [
                {
                  "lang": "en",
                  "value": "GENERAL"
                }
              ]
            },
            {
              "cvssV4_0": {
                "Automatable": "NOT_DEFINED",
                "Recovery": "NOT_DEFINED",
                "Safety": "NOT_DEFINED",
                "attackComplexity": "LOW",
                "attackRequirements": "PRESENT",
                "attackVector": "NETWORK",
                "baseScore": 6.3,
                "baseSeverity": "MEDIUM",
                "privilegesRequired": "NONE",
                "providerUrgency": "NOT_DEFINED",
                "subAvailabilityImpact": "NONE",
                "subConfidentialityImpact": "NONE",
                "subIntegrityImpact": "NONE",
                "userInteraction": "NONE",
                "valueDensity": "NOT_DEFINED",
                "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N",
                "version": "4.0",
                "vulnAvailabilityImpact": "LOW",
                "vulnConfidentialityImpact": "LOW",
                "vulnIntegrityImpact": "NONE",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
              },
              "format": "CVSS",
              "scenarios": [
                {
                  "lang": "en",
                  "value": "GENERAL"
                }
              ]
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-416",
                  "description": "CWE-416 Use After Free",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-05-13T14:12:43.588Z",
            "orgId": "9dacffd4-cb11-413f-8451-fbbfd4ddc0ab",
            "shortName": "f5"
          },
          "references": [
            {
              "tags": [
                "vendor-advisory",
                "patch"
              ],
              "url": "https://my.f5.com/manage/s/article/K000161021"
            }
          ],
          "source": {
            "discovery": "EXTERNAL"
          },
          "title": "NGINX ngx_http_ssl_module vulnerability",
          "x_generator": {
            "engine": "F5 SIRTBot v1.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "9dacffd4-cb11-413f-8451-fbbfd4ddc0ab",
        "assignerShortName": "f5",
        "cveId": "CVE-2026-40701",
        "datePublished": "2026-05-13T14:12:43.588Z",
        "dateReserved": "2026-04-30T23:04:27.950Z",
        "dateUpdated": "2026-05-13T16:07:37.463Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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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.

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.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.