{
    "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-2026-26962",
        "tracking": {
            "current_release_date": "2026-04-03T15:45:07.259469Z",
            "generator": {
                "date": "2026-02-17T15:00:00Z",
                "engine": {
                    "name": "V.E.L.M.A",
                    "version": "1.7"
                }
            },
            "id": "CVE-2026-26962",
            "initial_release_date": "2026-04-02T17:39:44.470341Z",
            "revision_history": [
                {
                    "date": "2026-04-02T17:39:44.470341Z",
                    "number": "1",
                    "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (1).| References created (1).| CWES updated (1)."
                },
                {
                    "date": "2026-04-02T17:39:46.074321Z",
                    "number": "2",
                    "summary": "NCSC Score created."
                },
                {
                    "date": "2026-04-02T18:26:19.829029Z",
                    "number": "3",
                    "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (1).| CWES updated (1)."
                },
                {
                    "date": "2026-04-02T18:26:22.358575Z",
                    "number": "4",
                    "summary": "NCSC Score updated."
                },
                {
                    "date": "2026-04-02T20:52:58.376494Z",
                    "number": "5",
                    "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (3).| CWES updated (1)."
                },
                {
                    "date": "2026-04-03T15:44:57.153857Z",
                    "number": "6",
                    "summary": "Source connected.| CVE status created. (valid)| EPSS created."
                },
                {
                    "date": "2026-04-03T15:45:05.719060Z",
                    "number": "7",
                    "summary": "NCSC Score updated."
                }
            ],
            "status": "interim",
            "version": "7"
        }
    },
    "product_tree": {
        "branches": [
            {
                "branches": [
                    {
                        "branches": [
                            {
                                "category": "product_version_range",
                                "name": "vers:unknown/>=3.2.0|<3.2.6",
                                "product": {
                                    "name": "vers:unknown/>=3.2.0|<3.2.6",
                                    "product_id": "CSAFPID-5985095"
                                }
                            }
                        ],
                        "category": "product_name",
                        "name": "rack"
                    }
                ],
                "category": "vendor",
                "name": "rack"
            }
        ]
    },
    "vulnerabilities": [
        {
            "cve": "CVE-2026-26962",
            "cwe": {
                "id": "CWE-93",
                "name": "Improper Neutralization of CRLF Sequences ('CRLF Injection')"
            },
            "notes": [
                {
                    "category": "description",
                    "text": "Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting. This issue has been patched in version 3.2.6.",
                    "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/26xxx/CVE-2026-26962.json"
                },
                {
                    "category": "description",
                    "text": "Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting. This issue has been patched in version 3.2.6.",
                    "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-26962"
                },
                {
                    "category": "description",
                    "text": "## Summary\n\n`Rack::Multipart::Parser` unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as `filename` or `name` instead of removing the folded line break during unfolding.\n\nAs a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting.\n\n## Details\n\n`Rack::Multipart::Parser` accepts folded multipart header values and unfolds them during parsing. However, the unfolding behavior does not fully remove the embedded line break sequence from the parsed value.\n\nThis means a multipart part header such as:\n\n```http\nContent-Disposition: form-data; name=\"file\"; filename=\"test\\r\\n foo.txt\"\n```\n\ncan result in a parsed parameter value that still contains CRLF characters.\n\nThe issue is not that Rack creates a second multipart header field. Rather, the problem is that CRLF remains embedded in the parsed metadata value after unfolding. If an application later uses that value in a security-sensitive context, such as constructing an HTTP response header, the preserved CRLF may alter downstream header parsing.\n\nAffected values may include multipart parameters such as `filename`, `name`, or similar parsed header attributes.\n\n## Impact\n\nApplications that accept multipart form uploads may be affected if they later reuse parsed multipart metadata in HTTP headers or other header-sensitive contexts.\n\nIn affected deployments, an attacker may be able to supply a multipart parameter value containing folded line breaks and cause downstream header injection, response splitting, cache poisoning, or related response parsing issues.\n\nThe practical impact depends on application behavior. If parsed multipart metadata is not reused in HTTP headers, the issue may be limited to incorrect parsing behavior rather than a direct exploit path.\n\n## Mitigation\n\n* Update to a patched version of Rack that removes CRLF correctly when unfolding folded multipart header values.\n* Avoid copying upload metadata such as `filename` directly into HTTP response headers without sanitization.\n* Sanitize or reject carriage return and line feed characters in multipart-derived values before reusing them in response headers, logs, or downstream protocol contexts.\n* Where feasible, normalize uploaded filenames before storing or reflecting them.",
                    "title": "github - https://api.github.com/advisories/GHSA-rx22-g9mx-qrhv"
                },
                {
                    "category": "other",
                    "text": "0.00039",
                    "title": "EPSS"
                },
                {
                    "category": "other",
                    "text": "4.2",
                    "title": "NCSC Score"
                },
                {
                    "category": "other",
                    "text": "Is related to (a version of) an uncommon product, There is cwe data available from source Nvd",
                    "title": "NCSC Score top decreasing factors"
                }
            ],
            "product_status": {
                "known_affected": [
                    "CSAFPID-5985095"
                ]
            },
            "references": [
                {
                    "category": "external",
                    "summary": "Source - cveprojectv5",
                    "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/26xxx/CVE-2026-26962.json"
                },
                {
                    "category": "external",
                    "summary": "Source - nvd",
                    "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-26962"
                },
                {
                    "category": "external",
                    "summary": "Source - github",
                    "url": "https://api.github.com/advisories/GHSA-rx22-g9mx-qrhv"
                },
                {
                    "category": "external",
                    "summary": "Source - first",
                    "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0"
                },
                {
                    "category": "external",
                    "summary": "Reference - cveprojectv5; github; nvd",
                    "url": "https://github.com/rack/rack/security/advisories/GHSA-rx22-g9mx-qrhv"
                },
                {
                    "category": "external",
                    "summary": "Reference - github",
                    "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26962"
                },
                {
                    "category": "external",
                    "summary": "Reference - github",
                    "url": "https://github.com/advisories/GHSA-rx22-g9mx-qrhv"
                }
            ],
            "scores": [
                {
                    "cvss_v3": {
                        "version": "3.1",
                        "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N",
                        "baseScore": 4.8,
                        "baseSeverity": "MEDIUM"
                    },
                    "products": [
                        "CSAFPID-5985095"
                    ]
                }
            ],
            "title": "CVE-2026-26962"
        }
    ]
}