Vulnerability-Lookup

CVE-2026-34166 (GCVE-0-2026-34166)

Vulnerability from cvelistv5 – Published: 2026-04-08 17:52 – Updated: 2026-04-10 20:37

Title

LiquidJS has a Memory Limit Bypass via Quadratic Amplification in `replace` Filter

Summary

LiquidJS is a Shopify / GitHub Pages compatible template engine in pure JavaScript. Prior to 10.25.3, the replace filter in LiquidJS incorrectly accounts for memory usage when the memoryLimit option is enabled. It charges str.length + pattern.length + replacement.length bytes to the memory limiter, but the actual output from str.split(pattern).join(replacement) can be quadratically larger when the pattern occurs many times in the input string. This allows an attacker who controls template content to bypass the memoryLimit DoS protection with approximately 2,500x amplification, potentially causing out-of-memory conditions. This vulnerability is fixed in 10.25.3.

Severity

3.7 (Low)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-400 - Uncontrolled Resource Consumption

Assigner

GitHub_M

References

3 references

URL	Tags
https://github.com/harttle/liquidjs/security/advi…	x_refsource_CONFIRM
https://github.com/harttle/liquidjs/commit/abc058…	x_refsource_MISC
https://github.com/harttle/liquidjs/releases/tag/…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
harttle	liquidjs	Affected: < 10.25.3

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-34166

Vulnerability from fkie_nvd - Published: 2026-04-08 19:25 - Updated: 2026-06-17 10:38

Severity

3.7 (Low) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Summary

References

URL	Tags
security-advisories@github.com	https://github.com/harttle/liquidjs/commit/abc058be0f33d6372cd2216f4945183167abeb25	Patch
security-advisories@github.com	https://github.com/harttle/liquidjs/releases/tag/v10.25.3	Release Notes
security-advisories@github.com	https://github.com/harttle/liquidjs/security/advisories/GHSA-mmg9-6m6j-jqqx	Exploit, Vendor Advisory

Impacted products

	Vendor	Product	Version
	liquidjs	liquidjs	*

JSON

To clipboard

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  "affected": [
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      "affectedData": [
        {
          "product": "liquidjs",
          "vendor": "harttle",
          "versions": [
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  "lastModified": "2026-06-17T10:38:35.957",
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GHSA-MMG9-6M6J-JQQX

Vulnerability from github – Published: 2026-04-08 15:00 – Updated: 2026-04-09 14:28

Summary

LiquidJS Has Memory Limit Bypass via Quadratic Amplification in `replace` Filter

Details

Summary

The replace filter in LiquidJS incorrectly accounts for memory usage when the memoryLimit option is enabled. It charges str.length + pattern.length + replacement.length bytes to the memory limiter, but the actual output from str.split(pattern).join(replacement) can be quadratically larger when the pattern occurs many times in the input string. This allows an attacker who controls template content to bypass the memoryLimit DoS protection with approximately 2,500x amplification, potentially causing out-of-memory conditions.

Details

The vulnerable code is in src/filters/string.ts:137-142:

export function replace (this: FilterImpl, v: string, pattern: string, replacement: string) {
  const str = stringify(v)
  pattern = stringify(pattern)
  replacement = stringify(replacement)
  this.context.memoryLimit.use(str.length + pattern.length + replacement.length)  // BUG: accounts for inputs, not output
  return str.split(pattern).join(replacement)  // actual output can be quadratically larger
}

The memoryLimit.use() call charges only the sum of the three input lengths. However, the str.split(pattern).join(replacement) operation produces output of size:

(number_of_occurrences * replacement.length) + non_matching_characters

When every character in str matches pattern (e.g., str = 5,000 as, pattern = a), there are 5,000 occurrences. With a 5,000-character replacement string, the output is 5000 * 5000 = 25,000,000 characters, while only 5000 + 1 + 5000 = 10,001 bytes are charged to the limiter.

The Limiter class at src/util/limiter.ts:3-22 is a simple accumulator — it only checks at the time use() is called and has no post-hoc validation of actual memory allocated.

The memoryLimit option defaults to Infinity (src/liquid-options.ts:198), so this only affects deployments that explicitly enable memory limiting to protect against untrusted template input.

PoC

const { Liquid } = require('liquidjs');

// User explicitly enables memoryLimit for DoS protection (10MB)
const engine = new Liquid({ memoryLimit: 1e7 });

const inputLen = 5000;
const aStr = 'a'.repeat(inputLen);
const bStr = 'b'.repeat(inputLen);

// Template that should be blocked by 10MB memory limit
const tpl = engine.parse(
  `{%- assign s = "${aStr}" -%}` +
  `{%- assign r = "${bStr}" -%}` +
  `{{ s | replace: "a", r }}`
);

// This should throw "memory alloc limit exceeded" but succeeds
const result = engine.renderSync(tpl);

console.log('Memory limit: 10,000,000 bytes');
console.log('Memory charged:', 10001, 'bytes');
console.log('Actual output:', result.length, 'bytes');  // 25,000,000 bytes
console.log('Amplification:', Math.round(result.length / 10001) + 'x');
// Output: Amplification: 2500x — completely bypasses the 10MB limit

Impact

Users who deploy LiquidJS with memoryLimit enabled to process untrusted templates (e.g., multi-tenant SaaS platforms allowing custom templates) are not protected against memory exhaustion via the replace filter. An attacker who can author templates can allocate ~2,500x more memory than the configured limit allows, potentially causing:

Node.js process out-of-memory crashes
Denial of service for co-tenant users on the same process
Resource exhaustion on the hosting infrastructure

The impact is limited to availability (no confidentiality or integrity impact), and requires both non-default configuration (memoryLimit enabled) and template authoring access.

Recommended Fix

Account for the actual output size in the memory limiter by calculating the number of occurrences:

export function replace (this: FilterImpl, v: string, pattern: string, replacement: string) {
  const str = stringify(v)
  pattern = stringify(pattern)
  replacement = stringify(replacement)
  const parts = str.split(pattern)
  const outputSize = str.length + (parts.length - 1) * (replacement.length - pattern.length)
  this.context.memoryLimit.use(outputSize)
  return parts.join(replacement)
}

This computes the exact output size: the original string length plus, for each occurrence, the difference between the replacement and pattern lengths. The split() result is reused to avoid computing it twice.

Severity

3.7 (Low)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 10.25.2"
      },
      "package": {
        "ecosystem": "npm",
        "name": "liquidjs"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "10.25.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-34166"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-08T15:00:29Z",
    "nvd_published_at": "2026-04-08T19:25:21Z",
    "severity": "LOW"
  },
  "details": "## Summary\n\nThe `replace` filter in LiquidJS incorrectly accounts for memory usage when the `memoryLimit` option is enabled. It charges `str.length + pattern.length + replacement.length` bytes to the memory limiter, but the actual output from `str.split(pattern).join(replacement)` can be quadratically larger when the pattern occurs many times in the input string. This allows an attacker who controls template content to bypass the `memoryLimit` DoS protection with approximately 2,500x amplification, potentially causing out-of-memory conditions.\n\n## Details\n\nThe vulnerable code is in `src/filters/string.ts:137-142`:\n\n```typescript\nexport function replace (this: FilterImpl, v: string, pattern: string, replacement: string) {\n  const str = stringify(v)\n  pattern = stringify(pattern)\n  replacement = stringify(replacement)\n  this.context.memoryLimit.use(str.length + pattern.length + replacement.length)  // BUG: accounts for inputs, not output\n  return str.split(pattern).join(replacement)  // actual output can be quadratically larger\n}\n```\n\nThe `memoryLimit.use()` call charges only the sum of the three input lengths. However, the `str.split(pattern).join(replacement)` operation produces output of size:\n\n```\n(number_of_occurrences * replacement.length) + non_matching_characters\n```\n\nWhen every character in `str` matches `pattern` (e.g., `str` = 5,000 `a`s, `pattern` = `a`), there are 5,000 occurrences. With a 5,000-character replacement string, the output is `5000 * 5000 = 25,000,000` characters, while only `5000 + 1 + 5000 = 10,001` bytes are charged to the limiter.\n\nThe `Limiter` class at `src/util/limiter.ts:3-22` is a simple accumulator \u2014 it only checks at the time `use()` is called and has no post-hoc validation of actual memory allocated.\n\nThe `memoryLimit` option defaults to `Infinity` (`src/liquid-options.ts:198`), so this only affects deployments that explicitly enable memory limiting to protect against untrusted template input.\n\n## PoC\n\n```javascript\nconst { Liquid } = require(\u0027liquidjs\u0027);\n\n// User explicitly enables memoryLimit for DoS protection (10MB)\nconst engine = new Liquid({ memoryLimit: 1e7 });\n\nconst inputLen = 5000;\nconst aStr = \u0027a\u0027.repeat(inputLen);\nconst bStr = \u0027b\u0027.repeat(inputLen);\n\n// Template that should be blocked by 10MB memory limit\nconst tpl = engine.parse(\n  `{%- assign s = \"${aStr}\" -%}` +\n  `{%- assign r = \"${bStr}\" -%}` +\n  `{{ s | replace: \"a\", r }}`\n);\n\n// This should throw \"memory alloc limit exceeded\" but succeeds\nconst result = engine.renderSync(tpl);\n\nconsole.log(\u0027Memory limit: 10,000,000 bytes\u0027);\nconsole.log(\u0027Memory charged:\u0027, 10001, \u0027bytes\u0027);\nconsole.log(\u0027Actual output:\u0027, result.length, \u0027bytes\u0027);  // 25,000,000 bytes\nconsole.log(\u0027Amplification:\u0027, Math.round(result.length / 10001) + \u0027x\u0027);\n// Output: Amplification: 2500x \u2014 completely bypasses the 10MB limit\n```\n\n## Impact\n\nUsers who deploy LiquidJS with `memoryLimit` enabled to process untrusted templates (e.g., multi-tenant SaaS platforms allowing custom templates) are not protected against memory exhaustion via the `replace` filter. An attacker who can author templates can allocate ~2,500x more memory than the configured limit allows, potentially causing:\n\n- Node.js process out-of-memory crashes\n- Denial of service for co-tenant users on the same process\n- Resource exhaustion on the hosting infrastructure\n\nThe impact is limited to availability (no confidentiality or integrity impact), and requires both non-default configuration (`memoryLimit` enabled) and template authoring access.\n\n## Recommended Fix\n\nAccount for the actual output size in the memory limiter by calculating the number of occurrences:\n\n```typescript\nexport function replace (this: FilterImpl, v: string, pattern: string, replacement: string) {\n  const str = stringify(v)\n  pattern = stringify(pattern)\n  replacement = stringify(replacement)\n  const parts = str.split(pattern)\n  const outputSize = str.length + (parts.length - 1) * (replacement.length - pattern.length)\n  this.context.memoryLimit.use(outputSize)\n  return parts.join(replacement)\n}\n```\n\nThis computes the exact output size: the original string length plus, for each occurrence, the difference between the replacement and pattern lengths. The `split()` result is reused to avoid computing it twice.",
  "id": "GHSA-mmg9-6m6j-jqqx",
  "modified": "2026-04-09T14:28:18Z",
  "published": "2026-04-08T15:00:29Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/harttle/liquidjs/security/advisories/GHSA-mmg9-6m6j-jqqx"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34166"
    },
    {
      "type": "WEB",
      "url": "https://github.com/harttle/liquidjs/commit/abc058be0f33d6372cd2216f4945183167abeb25"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/harttle/liquidjs"
    },
    {
      "type": "WEB",
      "url": "https://github.com/harttle/liquidjs/releases/tag/v10.25.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "LiquidJS Has Memory Limit Bypass via Quadratic Amplification in `replace` Filter"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

CVE-2026-34166 (GCVE-0-2026-34166)

FKIE_CVE-2026-34166

GHSA-MMG9-6M6J-JQQX

Summary

Details

PoC

Impact

Recommended Fix

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Nomenclature