{
    "document": {
        "category": "csaf_base",
        "csaf_version": "2.0",
        "distribution": {
            "tlp": {
                "label": "WHITE"
            }
        },
        "lang": "en",
        "notes": [
            {
                "category": "legal_disclaimer",
                "text": "The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this portal to enhance access to its information and vulnerabilities. The use of this information is subject to the following terms and conditions:\n\nThe vulnerabilities disclosed in this portal are gathered by NCSC-NL from a variety of open sources, which the user can retrieve from other platforms. NCSC-NL makes every reasonable effort to ensure that the content of this portal is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or real-time keeping up-to-date. NCSC-NL does not control nor guarantee the accuracy, relevance, timeliness or completeness of information obtained from these external sources. The vulnerabilities disclosed in this portal are intended solely for the convenience of professional parties to take appropriate measures to manage the risks posed to the cybersecurity. No rights can be derived from the information provided therein.\n\nNCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of the vulnerabilities disclosed in this portal. This includes damage resulting from the inaccuracy of incompleteness of the information contained in it.\nThe information on this page is subject to Dutch law. All disputes related to or arising from the use of this portal regarding the disclosure of vulnerabilities will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings."
            }
        ],
        "publisher": {
            "category": "coordinator",
            "contact_details": "cert@ncsc.nl",
            "name": "National Cyber Security Centre",
            "namespace": "https://www.ncsc.nl/"
        },
        "title": "CVE-2026-23440",
        "tracking": {
            "current_release_date": "2026-04-03T16:54:14.705919Z",
            "generator": {
                "date": "2026-02-17T15:00:00Z",
                "engine": {
                    "name": "V.E.L.M.A",
                    "version": "1.7"
                }
            },
            "id": "CVE-2026-23440",
            "initial_release_date": "2026-04-03T15:40:13.080797Z",
            "revision_history": [
                {
                    "date": "2026-04-03T15:40:13.080797Z",
                    "number": "1",
                    "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| Products created (5).| Products connected (7).| References created (5)."
                },
                {
                    "date": "2026-04-03T15:40:23.811229Z",
                    "number": "2",
                    "summary": "NCSC Score created."
                },
                {
                    "date": "2026-04-03T16:48:10.757397Z",
                    "number": "3",
                    "summary": "Source created.| CVE status created. (valid)| Description created for source.| References created (5)."
                }
            ],
            "status": "interim",
            "version": "3"
        }
    },
    "product_tree": {
        "branches": [
            {
                "branches": [
                    {
                        "branches": [
                            {
                                "category": "product_version_range",
                                "name": "vers:git/fef06678931ff67b158d337b581e5cf5ca40a3a3|<2051c709dce92da3550040aa7949cd5a9c89b14e",
                                "product": {
                                    "name": "vers:git/fef06678931ff67b158d337b581e5cf5ca40a3a3|<2051c709dce92da3550040aa7949cd5a9c89b14e",
                                    "product_id": "CSAFPID-5992324"
                                }
                            },
                            {
                                "category": "product_version_range",
                                "name": "vers:git/fef06678931ff67b158d337b581e5cf5ca40a3a3|<3dffc083292e6872787bd7e34b957627622f9af4",
                                "product": {
                                    "name": "vers:git/fef06678931ff67b158d337b581e5cf5ca40a3a3|<3dffc083292e6872787bd7e34b957627622f9af4",
                                    "product_id": "CSAFPID-5992323"
                                }
                            },
                            {
                                "category": "product_version_range",
                                "name": "vers:git/fef06678931ff67b158d337b581e5cf5ca40a3a3|<8d625c15471fb8780125eaef682983a96af77bdc",
                                "product": {
                                    "name": "vers:git/fef06678931ff67b158d337b581e5cf5ca40a3a3|<8d625c15471fb8780125eaef682983a96af77bdc",
                                    "product_id": "CSAFPID-5992326"
                                }
                            },
                            {
                                "category": "product_version_range",
                                "name": "vers:git/fef06678931ff67b158d337b581e5cf5ca40a3a3|<96c9c25b74686ac2de15921c9ad30c5ef13af8cd",
                                "product": {
                                    "name": "vers:git/fef06678931ff67b158d337b581e5cf5ca40a3a3|<96c9c25b74686ac2de15921c9ad30c5ef13af8cd",
                                    "product_id": "CSAFPID-5992325"
                                }
                            },
                            {
                                "category": "product_version_range",
                                "name": "vers:git/fef06678931ff67b158d337b581e5cf5ca40a3a3|<beb6e2e5976a128b0cccf10d158124422210c5ef",
                                "product": {
                                    "name": "vers:git/fef06678931ff67b158d337b581e5cf5ca40a3a3|<beb6e2e5976a128b0cccf10d158124422210c5ef",
                                    "product_id": "CSAFPID-5992327"
                                }
                            },
                            {
                                "category": "product_version_range",
                                "name": "vers:semver/6.12.78|<=6.12.*",
                                "product": {
                                    "name": "vers:semver/6.12.78|<=6.12.*",
                                    "product_id": "CSAFPID-5904671"
                                }
                            },
                            {
                                "category": "product_version_range",
                                "name": "vers:semver/6.18.20|<=6.18.*",
                                "product": {
                                    "name": "vers:semver/6.18.20|<=6.18.*",
                                    "product_id": "CSAFPID-5905005"
                                }
                            },
                            {
                                "category": "product_version_range",
                                "name": "vers:semver/6.19.10|<=6.19.*",
                                "product": {
                                    "name": "vers:semver/6.19.10|<=6.19.*",
                                    "product_id": "CSAFPID-5905006"
                                }
                            },
                            {
                                "category": "product_version_range",
                                "name": "vers:semver/6.6.130|<=6.6.*",
                                "product": {
                                    "name": "vers:semver/6.6.130|<=6.6.*",
                                    "product_id": "CSAFPID-5904647"
                                }
                            },
                            {
                                "category": "product_version_range",
                                "name": "vers:semver/<6.4",
                                "product": {
                                    "name": "vers:semver/<6.4",
                                    "product_id": "CSAFPID-1287532"
                                }
                            },
                            {
                                "category": "product_version_range",
                                "name": "vers:unknown/6.4",
                                "product": {
                                    "name": "vers:unknown/6.4",
                                    "product_id": "CSAFPID-1287531"
                                }
                            },
                            {
                                "category": "product_version_range",
                                "name": "vers:unknown/7.0-rc5|<=*",
                                "product": {
                                    "name": "vers:unknown/7.0-rc5|<=*",
                                    "product_id": "CSAFPID-5905027"
                                }
                            }
                        ],
                        "category": "product_name",
                        "name": "Linux"
                    }
                ],
                "category": "vendor",
                "name": "Linux"
            }
        ]
    },
    "vulnerabilities": [
        {
            "cve": "CVE-2026-23440",
            "notes": [
                {
                    "category": "description",
                    "text": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/mlx5e: Fix race condition during IPSec ESN update\n\nIn IPSec full offload mode, the device reports an ESN (Extended\nSequence Number) wrap event to the driver. The driver validates this\nevent by querying the IPSec ASO and checking that the esn_event_arm\nfield is 0x0, which indicates an event has occurred. After handling\nthe event, the driver must re-arm the context by setting esn_event_arm\nback to 0x1.\n\nA race condition exists in this handling path. After validating the\nevent, the driver calls mlx5_accel_esp_modify_xfrm() to update the\nkernel's xfrm state. This function temporarily releases and\nre-acquires the xfrm state lock.\n\nSo, need to acknowledge the event first by setting esn_event_arm to\n0x1. This prevents the driver from reprocessing the same ESN update if\nthe hardware sends events for other reason. Since the next ESN update\nonly occurs after nearly 2^31 packets are received, there's no risk of\nmissing an update, as it will happen long after this handling has\nfinished.\n\nProcessing the event twice causes the ESN high-order bits (esn_msb) to\nbe incremented incorrectly. The driver then programs the hardware with\nthis invalid ESN state, which leads to anti-replay failures and a\ncomplete halt of IPSec traffic.\n\nFix this by re-arming the ESN event immediately after it is validated,\nbefore calling mlx5_accel_esp_modify_xfrm(). This ensures that any\nspurious, duplicate events are correctly ignored, closing the race\nwindow.",
                    "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/23xxx/CVE-2026-23440.json"
                },
                {
                    "category": "description",
                    "text": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/mlx5e: Fix race condition during IPSec ESN update\n\nIn IPSec full offload mode, the device reports an ESN (Extended\nSequence Number) wrap event to the driver. The driver validates this\nevent by querying the IPSec ASO and checking that the esn_event_arm\nfield is 0x0, which indicates an event has occurred. After handling\nthe event, the driver must re-arm the context by setting esn_event_arm\nback to 0x1.\n\nA race condition exists in this handling path. After validating the\nevent, the driver calls mlx5_accel_esp_modify_xfrm() to update the\nkernel's xfrm state. This function temporarily releases and\nre-acquires the xfrm state lock.\n\nSo, need to acknowledge the event first by setting esn_event_arm to\n0x1. This prevents the driver from reprocessing the same ESN update if\nthe hardware sends events for other reason. Since the next ESN update\nonly occurs after nearly 2^31 packets are received, there's no risk of\nmissing an update, as it will happen long after this handling has\nfinished.\n\nProcessing the event twice causes the ESN high-order bits (esn_msb) to\nbe incremented incorrectly. The driver then programs the hardware with\nthis invalid ESN state, which leads to anti-replay failures and a\ncomplete halt of IPSec traffic.\n\nFix this by re-arming the ESN event immediately after it is validated,\nbefore calling mlx5_accel_esp_modify_xfrm(). This ensures that any\nspurious, duplicate events are correctly ignored, closing the race\nwindow.",
                    "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-23440"
                },
                {
                    "category": "other",
                    "text": "4.1",
                    "title": "NCSC Score"
                },
                {
                    "category": "other",
                    "text": "The value of the most recent CVSS (V3) score, Is related to a product by vendor Linux",
                    "title": "NCSC Score top decreasing factors"
                }
            ],
            "product_status": {
                "known_affected": [
                    "CSAFPID-1287531",
                    "CSAFPID-5992323",
                    "CSAFPID-5992324",
                    "CSAFPID-5992325",
                    "CSAFPID-5992326",
                    "CSAFPID-5992327"
                ],
                "known_not_affected": [
                    "CSAFPID-1287532",
                    "CSAFPID-5904647",
                    "CSAFPID-5904671",
                    "CSAFPID-5905005",
                    "CSAFPID-5905006",
                    "CSAFPID-5905027"
                ]
            },
            "references": [
                {
                    "category": "external",
                    "summary": "Source - cveprojectv5",
                    "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/23xxx/CVE-2026-23440.json"
                },
                {
                    "category": "external",
                    "summary": "Source - nvd",
                    "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-23440"
                },
                {
                    "category": "external",
                    "summary": "Reference - cveprojectv5; nvd",
                    "url": "https://git.kernel.org/stable/c/3dffc083292e6872787bd7e34b957627622f9af4"
                },
                {
                    "category": "external",
                    "summary": "Reference - cveprojectv5; nvd",
                    "url": "https://git.kernel.org/stable/c/2051c709dce92da3550040aa7949cd5a9c89b14e"
                },
                {
                    "category": "external",
                    "summary": "Reference - cveprojectv5; nvd",
                    "url": "https://git.kernel.org/stable/c/96c9c25b74686ac2de15921c9ad30c5ef13af8cd"
                },
                {
                    "category": "external",
                    "summary": "Reference - cveprojectv5; nvd",
                    "url": "https://git.kernel.org/stable/c/8d625c15471fb8780125eaef682983a96af77bdc"
                },
                {
                    "category": "external",
                    "summary": "Reference - cveprojectv5; nvd",
                    "url": "https://git.kernel.org/stable/c/beb6e2e5976a128b0cccf10d158124422210c5ef"
                }
            ],
            "title": "CVE-2026-23440"
        }
    ]
}