CVE-2026-56741 (GCVE-0-2026-56741)

Vulnerability from cvelistv5 – Published: 2026-07-17 21:15 – Updated: 2026-07-20 15:21
VLAI
Title
JLine: Unauthenticated Remote DoS via Unbounded Telnet NAWS Terminal Geometry
Summary
JLine is a Java library for handling console input. Prior to 3.30.14, 4.0.16, and 4.2.1, the JLine3 Telnet server remote-telnet module does not apply an upper bound to terminal dimensions received via the Telnet NAWS option, and TelnetIO.handleNAWS() in TelnetIO.java:856-879 reads client-supplied width and height as 16-bit unsigned integers and passes values such as 65535x65535 to setTerminalGeometry(), allowing an unauthenticated remote attacker to repeatedly alternate values and trigger continuous expensive rendering work that causes CPU exhaustion and denial of service. This issue is fixed in versions 3.30.14, 4.0.16, and 4.2.1.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: poc Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-20 15:21 UTC
CWE
  • CWE-400 - Uncontrolled Resource Consumption
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7926 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
jline jline3 Affected: < 3.30.14
Affected: >= 4.0.0, < 4.0.16
Affected: >= 4.1.0, < 4.2.1
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-56741",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-20T15:21:00.621662Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-20T15:21:23.382Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "jline3",
          "vendor": "jline",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.30.14"
            },
            {
              "status": "affected",
              "version": "\u003e= 4.0.0, \u003c 4.0.16"
            },
            {
              "status": "affected",
              "version": "\u003e= 4.1.0, \u003c 4.2.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "JLine is a Java library for handling console input. Prior to 3.30.14, 4.0.16, and 4.2.1, the JLine3 Telnet server remote-telnet module does not apply an upper bound to terminal dimensions received via the Telnet NAWS option, and TelnetIO.handleNAWS() in TelnetIO.java:856-879 reads client-supplied width and height as 16-bit unsigned integers and passes values such as 65535x65535 to setTerminalGeometry(), allowing an unauthenticated remote attacker to repeatedly alternate values and trigger continuous expensive rendering work that causes CPU exhaustion and denial of service. This issue is fixed in versions 3.30.14, 4.0.16, and 4.2.1."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-400",
              "description": "CWE-400: Uncontrolled Resource Consumption",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-17T21:15:14.732Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933"
        },
        {
          "name": "https://github.com/jline/jline3/pull/2000",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/jline/jline3/pull/2000"
        },
        {
          "name": "https://github.com/jline/jline3/commit/3ea9cad8699714dc072fade29d36be0d1e23d708",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/jline/jline3/commit/3ea9cad8699714dc072fade29d36be0d1e23d708"
        },
        {
          "name": "https://github.com/jline/jline3/commit/733eb353dca7b0ea0252e724445b6defa29c393e",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/jline/jline3/commit/733eb353dca7b0ea0252e724445b6defa29c393e"
        },
        {
          "name": "https://github.com/jline/jline3/commit/86b7ba7801988aadb1a67555629522a71d603bd3",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/jline/jline3/commit/86b7ba7801988aadb1a67555629522a71d603bd3"
        },
        {
          "name": "https://github.com/jline/jline3/releases/tag/4.0.16",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/jline/jline3/releases/tag/4.0.16"
        },
        {
          "name": "https://github.com/jline/jline3/releases/tag/4.2.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/jline/jline3/releases/tag/4.2.1"
        }
      ],
      "source": {
        "advisory": "GHSA-2r2c-cx56-8933",
        "discovery": "UNKNOWN"
      },
      "title": "JLine: Unauthenticated Remote DoS via Unbounded Telnet NAWS Terminal Geometry"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-56741",
    "datePublished": "2026-07-17T21:15:14.732Z",
    "dateReserved": "2026-06-22T19:17:28.959Z",
    "dateUpdated": "2026-07-20T15:21:23.382Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-56741",
      "date": "2026-10-28",
      "epss": "0.00595",
      "percentile": "0.48315"
    },
    "microsoft_vex": {
      "current_release_date": "2026-10-22T01:10:27.000Z",
      "cve": "CVE-2026-56741",
      "id": "msrc_CVE-2026-56741",
      "initial_release_date": "2026-10-22T01:10:27.000Z",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "JLine: Unauthenticated Remote DoS via Unbounded Telnet NAWS Terminal Geometry",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-56741.json",
      "version": "1"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "product": "jline3",
                "vendor": "jline",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003c 3.30.14"
                  },
                  {
                    "status": "affected",
                    "version": "\u003e= 4.0.0, \u003c 4.0.16"
                  },
                  {
                    "status": "affected",
                    "version": "\u003e= 4.1.0, \u003c 4.2.1"
                  }
                ]
              }
            ],
            "source": "security-advisories@github.com"
          }
        ],
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:a:jline:jline:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "7B951CA3-5A41-4A71-9C90-8377E53EC47A",
                    "versionEndExcluding": "3.30.14",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:a:jline:jline:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "0949B9BC-A091-477A-B578-92C86B0E5DE8",
                    "versionEndExcluding": "4.0.16",
                    "versionStartIncluding": "4.0.0",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:a:jline:jline:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "6431F876-039C-4BE1-ABE0-4BFCC22B6F49",
                    "versionEndExcluding": "4.2.1",
                    "versionStartIncluding": "4.1.0",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "JLine is a Java library for handling console input. Prior to 3.30.14, 4.0.16, and 4.2.1, the JLine3 Telnet server remote-telnet module does not apply an upper bound to terminal dimensions received via the Telnet NAWS option, and TelnetIO.handleNAWS() in TelnetIO.java:856-879 reads client-supplied width and height as 16-bit unsigned integers and passes values such as 65535x65535 to setTerminalGeometry(), allowing an unauthenticated remote attacker to repeatedly alternate values and trigger continuous expensive rendering work that causes CPU exhaustion and denial of service. This issue is fixed in versions 3.30.14, 4.0.16, and 4.2.1."
          },
          {
            "lang": "es",
            "value": "JLine es una biblioteca Java para manejar la entrada de consola. Antes de las versiones 3.30.14, 4.0.16 y 4.2.1, el m\u00f3dulo remote-telnet del servidor Telnet de JLine3 no aplica un l\u00edmite superior a las dimensiones del terminal recibidas a trav\u00e9s de la opci\u00f3n Telnet NAWS, y TelnetIO.handleNAWS() en TelnetIO.java:856-879 lee el ancho y alto proporcionados por el cliente como enteros sin signo de 16 bits y pasa valores como 65535x65535 a setTerminalGeometry(), permitiendo a un atacante remoto no autenticado alternar repetidamente los valores y desencadenar un trabajo de renderizado costoso y continuo que causa el agotamiento de la CPU y la denegaci\u00f3n de servicio. Este problema se ha solucionado en las versiones 3.30.14, 4.0.16 y 4.2.1."
          }
        ],
        "id": "CVE-2026-56741",
        "lastModified": "2026-10-24T20:10:00.137",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 7.5,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 3.9,
              "impactScore": 3.6,
              "source": "security-advisories@github.com",
              "type": "Secondary"
            }
          ],
          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
                "id": "CVE-2026-56741",
                "options": [
                  {
                    "exploitation": "poc"
                  },
                  {
                    "automatable": "yes"
                  },
                  {
                    "technicalImpact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-20T15:21:00.621662Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2026-07-17T22:17:57.317",
        "references": [
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Patch"
            ],
            "url": "https://github.com/jline/jline3/commit/3ea9cad8699714dc072fade29d36be0d1e23d708"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Patch"
            ],
            "url": "https://github.com/jline/jline3/commit/733eb353dca7b0ea0252e724445b6defa29c393e"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Patch"
            ],
            "url": "https://github.com/jline/jline3/commit/86b7ba7801988aadb1a67555629522a71d603bd3"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Issue Tracking"
            ],
            "url": "https://github.com/jline/jline3/pull/2000"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Release Notes"
            ],
            "url": "https://github.com/jline/jline3/releases/tag/4.0.16"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Release Notes"
            ],
            "url": "https://github.com/jline/jline3/releases/tag/4.2.1"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Vendor Advisory",
              "Exploit"
            ],
            "url": "https://github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933"
          },
          {
            "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
            "tags": [
              "Vendor Advisory",
              "Exploit"
            ],
            "url": "https://github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933"
          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Analyzed",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-400"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Secondary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-10-12T21:31:19+00:00",
      "cve": "CVE-2026-56741",
      "id": "CVE-2026-56741",
      "initial_release_date": "2026-07-17T21:15:14.732000+00:00",
      "product_status:known_not_affected": "9",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "org.jline/jline-remote-telnet: JLine3 Telnet server: Denial of Service via uncontrolled terminal dimensions",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-56741.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2026-56741",
                    "options": [
                      {
                        "Exploitation": "poc"
                      },
                      {
                        "Automatable": "yes"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-07-20T15:21:00.621662Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-07-20T15:21:18.349Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "references": [
              {
                "tags": [
                  "exploit"
                ],
                "url": "https://github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933"
              }
            ],
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "product": "jline3",
              "vendor": "jline",
              "versions": [
                {
                  "status": "affected",
                  "version": "\u003c 3.30.14"
                },
                {
                  "status": "affected",
                  "version": "\u003e= 4.0.0, \u003c 4.0.16"
                },
                {
                  "status": "affected",
                  "version": "\u003e= 4.1.0, \u003c 4.2.1"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "JLine is a Java library for handling console input. Prior to 3.30.14, 4.0.16, and 4.2.1, the JLine3 Telnet server remote-telnet module does not apply an upper bound to terminal dimensions received via the Telnet NAWS option, and TelnetIO.handleNAWS() in TelnetIO.java:856-879 reads client-supplied width and height as 16-bit unsigned integers and passes values such as 65535x65535 to setTerminalGeometry(), allowing an unauthenticated remote attacker to repeatedly alternate values and trigger continuous expensive rendering work that causes CPU exhaustion and denial of service. This issue is fixed in versions 3.30.14, 4.0.16, and 4.2.1."
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 7.5,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                "version": "3.1"
              }
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-400",
                  "description": "CWE-400: Uncontrolled Resource Consumption",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-07-17T21:15:14.732Z",
            "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
            "shortName": "GitHub_M"
          },
          "references": [
            {
              "name": "https://github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933",
              "tags": [
                "x_refsource_CONFIRM"
              ],
              "url": "https://github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933"
            },
            {
              "name": "https://github.com/jline/jline3/pull/2000",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/jline/jline3/pull/2000"
            },
            {
              "name": "https://github.com/jline/jline3/commit/3ea9cad8699714dc072fade29d36be0d1e23d708",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/jline/jline3/commit/3ea9cad8699714dc072fade29d36be0d1e23d708"
            },
            {
              "name": "https://github.com/jline/jline3/commit/733eb353dca7b0ea0252e724445b6defa29c393e",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/jline/jline3/commit/733eb353dca7b0ea0252e724445b6defa29c393e"
            },
            {
              "name": "https://github.com/jline/jline3/commit/86b7ba7801988aadb1a67555629522a71d603bd3",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/jline/jline3/commit/86b7ba7801988aadb1a67555629522a71d603bd3"
            },
            {
              "name": "https://github.com/jline/jline3/releases/tag/4.0.16",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/jline/jline3/releases/tag/4.0.16"
            },
            {
              "name": "https://github.com/jline/jline3/releases/tag/4.2.1",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/jline/jline3/releases/tag/4.2.1"
            }
          ],
          "source": {
            "advisory": "GHSA-2r2c-cx56-8933",
            "discovery": "UNKNOWN"
          },
          "title": "JLine: Unauthenticated Remote DoS via Unbounded Telnet NAWS Terminal Geometry"
        }
      },
      "cveMetadata": {
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "assignerShortName": "GitHub_M",
        "cveId": "CVE-2026-56741",
        "datePublished": "2026-07-17T21:15:14.732Z",
        "dateReserved": "2026-06-22T19:17:28.959Z",
        "dateUpdated": "2026-07-20T15:21:23.382Z",
        "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.