CVE-2026-15243 (GCVE-0-2026-15243)

Vulnerability from cvelistv5 – Published: 2026-07-24 11:29 – Updated: 2026-07-24 12:33 X_Open Source
VLAI
Title
Improper Validation of Certificate in CAS Client
Summary
Apereo CAS Client accepts any CA-trusted certificate for any hostname, provided the URL the client is calling matches the configured allowlist or regex. An attacker with a MITM position (DNS poisoning, rogue Wi-Fi, malicious proxy, etc.) can provide any CA-signed certificate for a hostname that matches the configured allowlist or regex. This can lead to intercepting the CAS exchange, capturing the Ticket-Granting Ticket (TGT), and subsequently obtaining Service Tickets on behalf of the victim.  Because maintainers contact attempts were unsuccessful, vulnerabilities have only been confirmed in version 4.1.0 (Java Apereo CAS Client) and 3.6.4 (Jasig CAS Client) but may also affect other versions.
Severity
7.4 (High)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-24 12:33 UTC
CWE
  • CWE-297 - Improper validation of certificate with host mismatch
Assigner
CERT-PL CNA under the ENISA root
CNA scorecard B 81/100 over 241 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Apereo Java Apereo CAS Client Affected: 4.1.0 (semver)
guessed Create a notification for this product.
Apereo Jasig CAS Client Affected: 3.6.4
guessed Create a notification for this product.
Credits
Rafał Łykowski (Qualtrics) Łukasz Kollbek (Qualtrics) Krzysztof Surówka (Qualtrics)
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-15243",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-24T12:33:47.532505Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-24T12:33:58.681Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unknown",
          "product": "Java Apereo CAS Client",
          "repo": "https://github.com/apereo/java-cas-client",
          "vendor": "Apereo",
          "versions": [
            {
              "status": "affected",
              "version": "4.1.0",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://mvnrepository.com/",
          "defaultStatus": "unknown",
          "packageName": "org.jasig.cas.client",
          "product": "Jasig CAS Client",
          "repo": "https://github.com/apereo/java-cas-client",
          "vendor": "Apereo",
          "versions": [
            {
              "status": "affected",
              "version": "3.6.4"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Rafa\u0142 \u0141ykowski (Qualtrics)"
        },
        {
          "lang": "en",
          "type": "finder",
          "value": "\u0141ukasz Kollbek (Qualtrics)"
        },
        {
          "lang": "en",
          "type": "finder",
          "value": "Krzysztof Sur\u00f3wka (Qualtrics)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "Apereo CAS Client\u0026nbsp;accepts any CA-trusted certificate for any hostname, provided the URL the client is calling matches the configured allowlist or regex. An attacker with a MITM position (DNS poisoning, rogue Wi-Fi, malicious proxy, etc.) can provide any CA-signed certificate for a hostname that matches the configured allowlist or regex. This can lead to\u003cspan\u003e\u0026nbsp;intercepting the CAS exchange, capturing the\u0026nbsp;\u003c/span\u003eTicket-Granting Ticket (\u003cspan\u003eTGT), and subsequently obtaining Service Tickets on behalf of the victim.\u0026nbsp;\u003c/span\u003e\u003cdiv\u003e\u003cdiv\u003e\u003cdiv\u003e\u003cbr\u003e\u003c/div\u003e\u003cdiv\u003eBecause maintainers contact attempts were unsuccessful, vulnerabilities have only been confirmed in version 4.1.0 (Java Apereo CAS Client) and\u0026nbsp;3.6.4 (Jasig CAS Client) but may also affect other versions.\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"
            }
          ],
          "value": "Apereo CAS Client\u00a0accepts any CA-trusted certificate for any hostname, provided the URL the client is calling matches the configured allowlist or regex. An attacker with a MITM position (DNS poisoning, rogue Wi-Fi, malicious proxy, etc.) can provide any CA-signed certificate for a hostname that matches the configured allowlist or regex. This can lead to\u00a0intercepting the CAS exchange, capturing the\u00a0Ticket-Granting Ticket (TGT), and subsequently obtaining Service Tickets on behalf of the victim.\u00a0\n\n\nBecause maintainers contact attempts were unsuccessful, vulnerabilities have only been confirmed in version 4.1.0 (Java Apereo CAS Client) and\u00a03.6.4 (Jasig CAS Client) but may also affect other versions."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 7.4,
            "baseSeverity": "HIGH",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "ACTIVE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-297",
              "description": "CWE-297 Improper validation of certificate with host mismatch",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-24T11:29:26.067Z",
        "orgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6",
        "shortName": "CERT-PL"
      },
      "references": [
        {
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://cert.pl/en/posts/2026/07/CVE-2026-15243"
        },
        {
          "tags": [
            "product"
          ],
          "url": "https://www.apereo.org/programs/software/cas"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "tags": [
        "x_open-source"
      ],
      "title": "Improper Validation of Certificate in CAS Client",
      "x_generator": {
        "engine": "Vulnogram 1.0.3"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6",
    "assignerShortName": "CERT-PL",
    "cveId": "CVE-2026-15243",
    "datePublished": "2026-07-24T11:29:26.067Z",
    "dateReserved": "2026-07-09T11:56:55.414Z",
    "dateUpdated": "2026-07-24T12:33:58.681Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-15243",
      "date": "2026-10-28",
      "epss": "0.0026",
      "percentile": "0.17685"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unknown",
                "product": "Java Apereo CAS Client",
                "repo": "https://github.com/apereo/java-cas-client",
                "vendor": "Apereo",
                "versions": [
                  {
                    "status": "affected",
                    "version": "4.1.0",
                    "versionType": "semver"
                  }
                ]
              },
              {
                "collectionURL": "https://mvnrepository.com/",
                "defaultStatus": "unknown",
                "packageName": "org.jasig.cas.client",
                "product": "Jasig CAS Client",
                "repo": "https://github.com/apereo/java-cas-client",
                "vendor": "Apereo",
                "versions": [
                  {
                    "status": "affected",
                    "version": "3.6.4"
                  }
                ]
              }
            ],
            "source": "cvd@cert.pl"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Apereo CAS Client\u00a0accepts any CA-trusted certificate for any hostname, provided the URL the client is calling matches the configured allowlist or regex. An attacker with a MITM position (DNS poisoning, rogue Wi-Fi, malicious proxy, etc.) can provide any CA-signed certificate for a hostname that matches the configured allowlist or regex. This can lead to\u00a0intercepting the CAS exchange, capturing the\u00a0Ticket-Granting Ticket (TGT), and subsequently obtaining Service Tickets on behalf of the victim.\u00a0\n\n\nBecause maintainers contact attempts were unsuccessful, vulnerabilities have only been confirmed in version 4.1.0 (Java Apereo CAS Client) and\u00a03.6.4 (Jasig CAS Client) but may also affect other versions."
          }
        ],
        "id": "CVE-2026-15243",
        "lastModified": "2026-09-03T04:15:17.710",
        "metrics": {
          "cvssMetricV40": [
            {
              "cvssData": {
                "Automatable": "NOT_DEFINED",
                "Recovery": "NOT_DEFINED",
                "Safety": "NOT_DEFINED",
                "attackComplexity": "LOW",
                "attackRequirements": "PRESENT",
                "attackVector": "NETWORK",
                "availabilityRequirement": "NOT_DEFINED",
                "baseScore": 7.4,
                "baseSeverity": "HIGH",
                "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": "ACTIVE",
                "valueDensity": "NOT_DEFINED",
                "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/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": "NONE",
                "vulnConfidentialityImpact": "HIGH",
                "vulnIntegrityImpact": "HIGH",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
              },
              "source": "cvd@cert.pl",
              "type": "Secondary"
            }
          ],
          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
                "id": "CVE-2026-15243",
                "options": [
                  {
                    "exploitation": "none"
                  },
                  {
                    "automatable": "no"
                  },
                  {
                    "technicalImpact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-24T12:33:47.532505Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2026-07-24T12:16:46.973",
        "references": [
          {
            "source": "cvd@cert.pl",
            "url": "https://cert.pl/en/posts/2026/07/CVE-2026-15243"
          },
          {
            "source": "cvd@cert.pl",
            "url": "https://www.apereo.org/programs/software/cas"
          }
        ],
        "sourceIdentifier": "cvd@cert.pl",
        "vulnStatus": "Awaiting Analysis",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-297"
              }
            ],
            "source": "cvd@cert.pl",
            "type": "Secondary"
          }
        ]
      }
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2026-15243",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-07-24T12:33:47.532505Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-07-24T12:33:54.585Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "defaultStatus": "unknown",
              "product": "Java Apereo CAS Client",
              "repo": "https://github.com/apereo/java-cas-client",
              "vendor": "Apereo",
              "versions": [
                {
                  "status": "affected",
                  "version": "4.1.0",
                  "versionType": "semver"
                }
              ]
            },
            {
              "collectionURL": "https://mvnrepository.com/",
              "defaultStatus": "unknown",
              "packageName": "org.jasig.cas.client",
              "product": "Jasig CAS Client",
              "repo": "https://github.com/apereo/java-cas-client",
              "vendor": "Apereo",
              "versions": [
                {
                  "status": "affected",
                  "version": "3.6.4"
                }
              ]
            }
          ],
          "credits": [
            {
              "lang": "en",
              "type": "finder",
              "value": "Rafa\u0142 \u0141ykowski (Qualtrics)"
            },
            {
              "lang": "en",
              "type": "finder",
              "value": "\u0141ukasz Kollbek (Qualtrics)"
            },
            {
              "lang": "en",
              "type": "finder",
              "value": "Krzysztof Sur\u00f3wka (Qualtrics)"
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "supportingMedia": [
                {
                  "base64": false,
                  "type": "text/html",
                  "value": "Apereo CAS Client\u0026nbsp;accepts any CA-trusted certificate for any hostname, provided the URL the client is calling matches the configured allowlist or regex. An attacker with a MITM position (DNS poisoning, rogue Wi-Fi, malicious proxy, etc.) can provide any CA-signed certificate for a hostname that matches the configured allowlist or regex. This can lead to\u003cspan\u003e\u0026nbsp;intercepting the CAS exchange, capturing the\u0026nbsp;\u003c/span\u003eTicket-Granting Ticket (\u003cspan\u003eTGT), and subsequently obtaining Service Tickets on behalf of the victim.\u0026nbsp;\u003c/span\u003e\u003cdiv\u003e\u003cdiv\u003e\u003cdiv\u003e\u003cbr\u003e\u003c/div\u003e\u003cdiv\u003eBecause maintainers contact attempts were unsuccessful, vulnerabilities have only been confirmed in version 4.1.0 (Java Apereo CAS Client) and\u0026nbsp;3.6.4 (Jasig CAS Client) but may also affect other versions.\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"
                }
              ],
              "value": "Apereo CAS Client\u00a0accepts any CA-trusted certificate for any hostname, provided the URL the client is calling matches the configured allowlist or regex. An attacker with a MITM position (DNS poisoning, rogue Wi-Fi, malicious proxy, etc.) can provide any CA-signed certificate for a hostname that matches the configured allowlist or regex. This can lead to\u00a0intercepting the CAS exchange, capturing the\u00a0Ticket-Granting Ticket (TGT), and subsequently obtaining Service Tickets on behalf of the victim.\u00a0\n\n\nBecause maintainers contact attempts were unsuccessful, vulnerabilities have only been confirmed in version 4.1.0 (Java Apereo CAS Client) and\u00a03.6.4 (Jasig CAS Client) but may also affect other versions."
            }
          ],
          "metrics": [
            {
              "cvssV4_0": {
                "Automatable": "NOT_DEFINED",
                "Recovery": "NOT_DEFINED",
                "Safety": "NOT_DEFINED",
                "attackComplexity": "LOW",
                "attackRequirements": "PRESENT",
                "attackVector": "NETWORK",
                "baseScore": 7.4,
                "baseSeverity": "HIGH",
                "exploitMaturity": "NOT_DEFINED",
                "privilegesRequired": "NONE",
                "providerUrgency": "NOT_DEFINED",
                "subAvailabilityImpact": "NONE",
                "subConfidentialityImpact": "NONE",
                "subIntegrityImpact": "NONE",
                "userInteraction": "ACTIVE",
                "valueDensity": "NOT_DEFINED",
                "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
                "version": "4.0",
                "vulnAvailabilityImpact": "NONE",
                "vulnConfidentialityImpact": "HIGH",
                "vulnIntegrityImpact": "HIGH",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
              },
              "format": "CVSS",
              "scenarios": [
                {
                  "lang": "en",
                  "value": "GENERAL"
                }
              ]
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-297",
                  "description": "CWE-297 Improper validation of certificate with host mismatch",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-07-24T11:29:26.067Z",
            "orgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6",
            "shortName": "CERT-PL"
          },
          "references": [
            {
              "tags": [
                "third-party-advisory"
              ],
              "url": "https://cert.pl/en/posts/2026/07/CVE-2026-15243"
            },
            {
              "tags": [
                "product"
              ],
              "url": "https://www.apereo.org/programs/software/cas"
            }
          ],
          "source": {
            "discovery": "EXTERNAL"
          },
          "tags": [
            "x_open-source"
          ],
          "title": "Improper Validation of Certificate in CAS Client",
          "x_generator": {
            "engine": "Vulnogram 1.0.3"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6",
        "assignerShortName": "CERT-PL",
        "cveId": "CVE-2026-15243",
        "datePublished": "2026-07-24T11:29:26.067Z",
        "dateReserved": "2026-07-09T11:56:55.414Z",
        "dateUpdated": "2026-07-24T12:33:58.681Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

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.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON

Loading timeline…




    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.