{ "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-2026-27018", "tracking": { "current_release_date": "2026-03-31T19:55:23.202815Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-27018", "initial_release_date": "2026-03-30T16:52:59.162739Z", "revision_history": [ { "date": "2026-03-30T16:52:59.162739Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (6).| CWES updated (1)." }, { "date": "2026-03-30T16:53:06.602162Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-03-30T20:38:42.348214Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (4).| CWES updated (1)." }, { "date": "2026-03-30T20:38:50.858463Z", "number": "4", "summary": "NCSC Score updated." }, { "date": "2026-03-30T21:25:22.063745Z", "number": "5", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (4).| CWES updated (1)." }, { "date": "2026-03-30T21:25:24.090609Z", "number": "6", "summary": "NCSC Score updated." }, { "date": "2026-03-31T15:39:12.787189Z", "number": "7", "summary": "Unknown change." }, { "date": "2026-03-31T15:39:15.336749Z", "number": "8", "summary": "NCSC Score updated." }, { "date": "2026-03-31T17:09:54.194020Z", "number": "9", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-31T17:09:59.370304Z", "number": "10", "summary": "NCSC Score updated." }, { "date": "2026-03-31T19:55:21.534081Z", "number": "11", "summary": "References created (1)." } ], "status": "interim", "version": "11" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<8.29.0", "product": { "name": "vers:unknown/<8.29.0", "product_id": "CSAFPID-5965610" } } ], "category": "product_name", "name": "gotenberg" } ], "category": "vendor", "name": "gotenberg" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-27018", "cwe": { "id": "CWE-22", "name": "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')" }, "notes": [ { "category": "description", "text": "### Impact\n\nThe fix introduced in version 8.1.0 for GHSA-rh2x-ccvw-q7r3 (CVE-2024-21527) can be bypassed using mixed-case or uppercase URL schemes.\n\nThe default `--chromium-deny-list` value is `^file:(?!//\\/tmp/).*`. This regex is anchored to lowercase `file:` at the start. However, per RFC 3986 Section 3.1, URI schemes are case-insensitive. Chromium normalizes the scheme to lowercase before navigation, so a URL like `FILE:///etc/passwd` or `File:///etc/passwd` bypasses the deny-list check but still gets resolved by Chromium as `file:///etc/passwd`.\n\nThe root cause is in `pkg/gotenberg/filter.go` — the `FilterDeadline` function compiles the deny-list regex with `regexp2.MustCompile(denied.String(), 0)`, where `0` means no flags (case-sensitive). Since the regex pattern itself doesn't include a `(?i)` flag, matching is strictly case-sensitive.\n\nThis affects both the URL endpoint and HTML conversion (via iframes, link tags, etc.).\n\n### Steps to Reproduce\n\n1. Start Gotenberg with default settings:\n\n```bash\ndocker run --rm -p 3000:3000 gotenberg/gotenberg:8.26.0 gotenberg\n```\n\n2. Read `/etc/passwd` via the URL endpoint using an uppercase scheme:\n\n```bash\ncurl -X POST 'http://localhost:3000/forms/chromium/convert/url' \\\n --form 'url=FILE:///etc/passwd' -o output.pdf\n```\n\n3. Open `output.pdf` — it contains the contents of `/etc/passwd`.\n\n4. Alternatively, create an `index.html`:\n\n```html\n\n```\n\nThen convert it:\n\n```bash\ncurl -X POST 'http://localhost:3000/forms/chromium/convert/html' \\\n -F 'files=@index.html' -o output.pdf\n```\n\n5. The resulting PDF contains `/etc/passwd` contents.\n\nMixed-case variants like `File:`, `fILE:`, `fiLE:` etc. all work as well.\n\n### Root Cause\n\n- `pkg/modules/chromium/chromium.go` defines the default deny-list as `^file:(?!//\\/tmp/).*`\n- `pkg/gotenberg/filter.go` compiles this with `regexp2.MustCompile(denied.String(), 0)` — flag `0` means case-sensitive\n- `pkg/modules/chromium/events.go` uses `FilterDeadline` to check intercepted request URLs against the deny-list\n- Chromium normalizes URL schemes to lowercase, so `FILE:///etc/passwd` becomes `file:///etc/passwd` after the deny-list check has already passed\n\n### Suggested Fix\n\nChange the default deny-list regex to use a case-insensitive flag:\n\n```\n(?i)^file:(?!//\\/tmp/).*\n```\n\nOr apply case-insensitive matching in `FilterDeadline` when compiling the regex.\n\n### Severity\n\nThis is effectively the same impact as CVE-2024-21527 — unauthenticated arbitrary file read from the Gotenberg container. An attacker can leak environment variables, configuration, credentials, and other sensitive data.", "title": "github - https://api.github.com/advisories/GHSA-jjwv-57xh-xr6r" }, { "category": "description", "text": "Gotenberg is an API for converting document formats. Prior to version 8.29.0, the fix introduced for CVE-2024-21527 can be bypassed using mixed-case or uppercase URL schemes. This issue has been patched in version 8.29.0.", "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/27xxx/CVE-2026-27018.json" }, { "category": "description", "text": "Gotenberg is an API for converting document formats. Prior to version 8.29.0, the fix introduced for CVE-2024-21527 can be bypassed using mixed-case or uppercase URL schemes. This issue has been patched in version 8.29.0.", "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-27018" }, { "category": "other", "text": "0.00016", "title": "EPSS" }, { "category": "other", "text": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:P", "title": "CVSSV4" }, { "category": "other", "text": "7.8", "title": "CVSSV4 base score" }, { "category": "other", "text": "3.7", "title": "NCSC Score" }, { "category": "other", "text": "There is cwe data available from source Github, There is cwe data available from source Nvd, Is related to (a version of) an uncommon product, The value of the most recent EPSS score, The value of the most recent CVSS (V3) score", "title": "NCSC Score top decreasing factors" } ], "product_status": { "known_affected": [ "CSAFPID-5965610" ] }, "references": [ { "category": "external", "summary": "Source - github", "url": "https://api.github.com/advisories/GHSA-jjwv-57xh-xr6r" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/27xxx/CVE-2026-27018.json" }, { "category": "external", "summary": "Source - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-27018" }, { "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/gotenberg/gotenberg/security/advisories/GHSA-jjwv-57xh-xr6r" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/gotenberg/gotenberg/security/advisories/GHSA-rh2x-ccvw-q7r3" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/gotenberg/gotenberg/commit/06b2b2e10c52b58135edbfe82e94d599eb0c5a11" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/gotenberg/gotenberg/commit/8625a4e899eb75e6fcf46d28394334c7fd79fff5" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/gotenberg/gotenberg/releases/tag/v8.29.0" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/advisories/GHSA-jjwv-57xh-xr6r" }, { "category": "external", "summary": "Reference - github", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27018" } ], "title": "CVE-2026-27018" } ] }