{"id":"CVE-2026-42267","aliases":["EUVD-2026-28506","GHSA-3xc2-h5r3-wv3r"],"status":"published","title":"Kimai: Formula Injection via tag names in XLSX export","description":"Kimai is an open-source time tracking application. From version 2.27.0 to before version 2.54.0, any ROLE_USER can create a tag with a formula string as its name (e.g. =SUM(54+51)) via POST /api/tags and assign it to a timesheet. When an admin exports timesheets to XLSX, ArrayFormatter.formatValue() joins tag names with implode() and returns the result unchanged. OpenSpout promotes any =-prefixed string to a FormulaCell, writing \u003cf\u003eSUM(54+51)\u003c/f\u003e into the XLSX archive. Excel evaluates the formula when the file is opened. This issue has been patched in version 2.54.0.","severity":{"version":"4.0","score":5.4,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.0022,"percentile":0.1266,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1236"],"published":"2026-05-05T20:53:38Z","modified":"2026-10-28T02:31:10Z","fixes":[{"ecosystem":"Packagist","package":"kimai/kimai","fixed_in":["2.54.0"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Packagist","package":"kimai/kimai","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.27.0"},{"last_affected":"2.53.0"},{"fixed":"2.54.0"}]}]},{"source":"osv","ecosystem":"Packagist","package":"kimai/kimai","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.27.0"},{"fixed":"2.54.0"}]}],"versions":["2.27.0","2.28.0","2.29.0","2.30.0","2.31.0","2.32.0","2.33.0","2.34.0","2.35.0","2.35.1","2.36.0","2.36.1","2.37.0","2.38.0","2.39.0","2.40.0","2.41.0","2.42.0","2.43.0","2.44.0","2.45.0","2.46.0","2.47.0","2.48.0","2.49.0","2.50.0","2.51.0","2.52.0","2.53.0"]}],"products":[{"vendor":"kimai","product":"kimai"}],"references":[{"url":"https://github.com/kimai/kimai/security/advisories/GHSA-3xc2-h5r3-wv3r","tags":["x_refsource_CONFIRM","exploit","Exploit","Mitigation","Vendor Advisory","advisory","web"]},{"url":"https://github.com/kimai/kimai/releases/tag/2.54.0","tags":["x_refsource_MISC","Product","Release Notes","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42267","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-3xc2-h5r3-wv3r"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42267.json","tags":["advisory"]},{"url":"https://github.com/kimai/kimai","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-42267","title":"Kimai: Formula Injection via tag names in XLSX export","description":"Kimai is an open-source time tracking application. From version 2.27.0 to before version 2.54.0, any ROLE_USER can create a tag with a formula string as its name (e.g. =SUM(54+51)) via POST /api/tags and assign it to a timesheet. When an admin exports timesheets to XLSX, ArrayFormatter.formatValue() joins tag names with implode() and returns the result unchanged. OpenSpout promotes any =-prefixed string to a FormulaCell, writing \u003cf\u003eSUM(54+51)\u003c/f\u003e into the XLSX archive. Excel evaluates the formula when the file is opened. This issue has been patched in version 2.54.0.","status":"published","published":"2026-05-08T03:28:52.226Z","modified":"2026-05-08T12:58:12.77Z","cvss":[{"version":"4.0","score":5.4,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P","level":"medium","assessor":"cna"}],"cwes":["CWE-1236"],"updated_at":"2026-11-02T13:40:23.731501Z"}],"euvd":[{"id":"EUVD-2026-28506","description":"Kimai is an open-source time tracking application. From version 2.27.0 to before version 2.54.0, any ROLE_USER can create a tag with a formula string as its name (e.g. =SUM(54+51)) via POST /api/tags and assign it to a timesheet. When an admin exports timesheets to XLSX, ArrayFormatter.formatValue() joins tag names with implode() and returns the result unchanged. OpenSpout promotes any =-prefixed string to a FormulaCell, writing \u003cf\u003eSUM(54+51)\u003c/f\u003e into the XLSX archive. Excel evaluates the formula when the file is opened. This issue has been patched in version 2.54.0.","status":"published","published":"2026-05-08T03:28:52Z","modified":"2026-05-08T12:58:12Z","cvss":[{"version":"4.0","score":5.4,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P","level":"medium"}],"updated_at":"2026-11-02T19:05:14.505765Z"}],"ghsa":[{"id":"GHSA-3xc2-h5r3-wv3r","title":"Kimai vulnerable to formula Injection via tag names in XLSX export","description":"## Summary\n\nAny `ROLE_USER` can create a tag with a formula string as its name (e.g. `=SUM(54+51)`) via `POST /api/tags` and assign it to a timesheet. When an admin exports timesheets to XLSX, `ArrayFormatter.formatValue()` joins tag names with `implode()` and returns the result unchanged. OpenSpout promotes any `=`-prefixed string to a `FormulaCell`, writing `\u003cf\u003eSUM(54+51)\u003c/f\u003e` into the XLSX archive. Excel evaluates the formula when the file is opened.\n\n## Details\n\n### 1. `ArrayFormatter` does not sanitize before returning\n\n`sanitizeDDE()` exists on `StringHelper` and is called by `TextFormatter`, but `ArrayFormatter` never calls it.\n```php\n// src/Export/Package/CellFormatter/ArrayFormatter.php:24\nreturn implode(', ', $value);  // no sanitizeDDE() call\n```\n\n### 2. Tag name validation does not block formula trigger characters\n\nThe API blocks commas in tag names but permits `=`, `+`, `-`, and `@` - all valid formula prefixes in Excel and LibreOffice Calc.\n\n### 3. OpenSpout silently promotes strings to formula cells\n\n`Cell::fromValue(\"=SUM(54+51)\")` returns a `FormulaCell` with no warning.\n\n### PoC\n\n1. It logs in as normal user, creates tag `=SUM(54+51)`, assigns it to a timesheet.\n2. Admin has to export timesheets to Excel version via `/en/export/` endpoint.\n\n\u003cimg width=\"1339\" height=\"700\" alt=\"image\" src=\"https://github.com/user-attachments/assets/884c7943-5e3b-4647-8bcc-e264d6719d66\" /\u003e\n\n\u003cimg width=\"1304\" height=\"128\" alt=\"formula_injection_tags\" src=\"https://github.com/user-attachments/assets/ef28f2ad-7491-4a15-bb18-1fcd6ff5e55a\" /\u003e\n\n## Impact\n\n- Any `ROLE_USER` can plant a formula that executes on the workstation of any user who exports and opens timesheet data\n- A single malicious tag poisons all future exports across all users and date ranges until the tag is deleted\n\n## Fixes\n\n1. Prevent `=` being part of the tag name (and other fields as well)\n2. Use OpenSpout `TextCell` for everything that is a string","status":"published","published":"2026-05-05T20:53:38Z","modified":"2026-05-14T20:31:09Z","cvss":[{"version":"4.0","score":5.4,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P","level":"medium"},{"version":"3.1","score":5.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N","level":"medium"}],"cwes":["CWE-1236"],"updated_at":"2026-11-02T14:40:09.033429Z"}],"nvd":[{"id":"CVE-2026-42267","description":"Kimai is an open-source time tracking application. From version 2.27.0 to before version 2.54.0, any ROLE_USER can create a tag with a formula string as its name (e.g. =SUM(54+51)) via POST /api/tags and assign it to a timesheet. When an admin exports timesheets to XLSX, ArrayFormatter.formatValue() joins tag names with implode() and returns the result unchanged. OpenSpout promotes any =-prefixed string to a FormulaCell, writing \u003cf\u003eSUM(54+51)\u003c/f\u003e into the XLSX archive. Excel evaluates the formula when the file is opened. This issue has been patched in version 2.54.0.","status":"published","published":"2026-05-08T04:16:20.533Z","modified":"2026-06-17T10:47:36.33Z","cvss":[{"version":"4.0","score":5.4,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P/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","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-1236"],"updated_at":"2026-11-02T14:12:17.842772Z"}],"osv":[{"id":"CVE-2026-42267","title":"Kimai: Formula Injection via tag names in XLSX export","description":"Kimai is an open-source time tracking application. From version 2.27.0 to before version 2.54.0, any ROLE_USER can create a tag with a formula string as its name (e.g. =SUM(54+51)) via POST /api/tags and assign it to a timesheet. When an admin exports timesheets to XLSX, ArrayFormatter.formatValue() joins tag names with implode() and returns the result unchanged. OpenSpout promotes any =-prefixed string to a FormulaCell, writing \u003cf\u003eSUM(54+51)\u003c/f\u003e into the XLSX archive. Excel evaluates the formula when the file is opened. This issue has been patched in version 2.54.0.","status":"published","published":"2026-05-08T03:28:52.226Z","modified":"2026-10-28T02:31:10.956239987Z","cvss":[{"version":"4.0","score":5.4,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P","level":"medium"}],"cwes":["CWE-1236"],"updated_at":"2026-11-02T15:45:04.117819Z"},{"id":"GHSA-3xc2-h5r3-wv3r","title":"Kimai vulnerable to formula Injection via tag names in XLSX export","description":"## Summary\n\nAny `ROLE_USER` can create a tag with a formula string as its name (e.g. `=SUM(54+51)`) via `POST /api/tags` and assign it to a timesheet. When an admin exports timesheets to XLSX, `ArrayFormatter.formatValue()` joins tag names with `implode()` and returns the result unchanged. OpenSpout promotes any `=`-prefixed string to a `FormulaCell`, writing `\u003cf\u003eSUM(54+51)\u003c/f\u003e` into the XLSX archive. Excel evaluates the formula when the file is opened.\n\n## Details\n\n### 1. `ArrayFormatter` does not sanitize before returning\n\n`sanitizeDDE()` exists on `StringHelper` and is called by `TextFormatter`, but `ArrayFormatter` never calls it.\n```php\n// src/Export/Package/CellFormatter/ArrayFormatter.php:24\nreturn implode(', ', $value);  // no sanitizeDDE() call\n```\n\n### 2. Tag name validation does not block formula trigger characters\n\nThe API blocks commas in tag names but permits `=`, `+`, `-`, and `@` - all valid formula prefixes in Excel and LibreOffice Calc.\n\n### 3. OpenSpout silently promotes strings to formula cells\n\n`Cell::fromValue(\"=SUM(54+51)\")` returns a `FormulaCell` with no warning.\n\n### PoC\n\n1. It logs in as normal user, creates tag `=SUM(54+51)`, assigns it to a timesheet.\n2. Admin has to export timesheets to Excel version via `/en/export/` endpoint.\n\n\u003cimg width=\"1339\" height=\"700\" alt=\"image\" src=\"https://github.com/user-attachments/assets/884c7943-5e3b-4647-8bcc-e264d6719d66\" /\u003e\n\n\u003cimg width=\"1304\" height=\"128\" alt=\"formula_injection_tags\" src=\"https://github.com/user-attachments/assets/ef28f2ad-7491-4a15-bb18-1fcd6ff5e55a\" /\u003e\n\n## Impact\n\n- Any `ROLE_USER` can plant a formula that executes on the workstation of any user who exports and opens timesheet data\n- A single malicious tag poisons all future exports across all users and date ranges until the tag is deleted\n\n## Fixes\n\n1. Prevent `=` being part of the tag name (and other fields as well)\n2. Use OpenSpout `TextCell` for everything that is a string","status":"published","published":"2026-05-05T20:53:38Z","modified":"2026-05-14T20:48:37.80019Z","cvss":[{"version":"3.1","score":5.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N","level":"medium"},{"version":"4.0","score":5.4,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P","level":"medium"}],"cwes":["CWE-1236"],"updated_at":"2026-11-02T15:46:36.092962Z"}]}}