CVE-2026-55575

LiquidJS: `pop` filter bypasses `memoryLimit` accounting that its array-filter siblings enforce

Published

2026-07-24

Modified

2026-07-24

EPSS percentile

31%

Aliases

GHSA-g357-x5c3-c72p

Sources

github-advisory

Summary

# `pop` filter bypasses `memoryLimit` accounting that its array-filter siblings enforce **CWE**: CWE-770 (Allocation of Resources Without Limits or Throttling) — sibling class of GHSA-8xx9-69p8-7jp3 and GHSA-2546-xv4c-mc8g, applied to `memoryLimit` instead of `renderLimit` ## Summary The `pop` array filter at `src/filters/array.ts:91-95` allocates a full clone of its input array via `[...toArray(v)]` but does **not** call `this.context.memoryLimit.use(...)` the way every other array-clone filter in the same file does (`shift`, `unshift`, `compact`, `concat`, `reverse`, `sample`, `slice`, `map`, `sortBy`, `where`, `group_by`, `uniq`). This silently disables the `memoryLimit` budget for `{{ huge_array | pop }}`, letting a template render allocate an O(N) clone of an attacker-influenced array regardless of how strictly `memoryLimit` is set. ## Affected - liquidjs ≥ all versions that ship the current `pop` filter implementation (verified `10.27.0`, HEAD `a8fd734b5`) - Deployments where any template uses `{{ arr | pop }}` on an array whose length is influenced by untrusted input (typical multi-tenant context arrays: orders, log lines, catalog entries, user lists, etc.) ## Vulnerability details ### Code `src/filters/array.ts:91-95`: ```ts export function pop (v: T[]): T[] { const clone = [...toArray(v)] // O(N) allocation — not charged to memoryLimit clone.pop() return clone } ``` Note: the function signature does not even declare `this: FilterImpl`, so it has no typed access to `this.context.memoryLimit` at the type level — a visual tell that the author skipped the limit-accounting boilerplate the surrounding filters use. Compare with `shift` (`src/filters/array.ts:97-103`), which is functionally identical except for the array-end operated on: ```ts export function shift (this: FilterImpl, v: T[]): T[] { const array = toArray(v) this.context.memoryLimit.use(array.length) // ← guard present const clone = [...array] clone.shift() return clone } ``` And `unshift`, `compact`, `concat`, `reverse`, `sample`, `slice`, `map`, `sortBy`, `where`, `group_by`, `uniq` — all of which also charge `memoryLimit.use(array.length)` (or `lhs.length + rhs.length` etc.) before allocating their working buffer. The asymmetry confirms `pop` is an accidental omission, not by design. ### Why the bypass matters `memoryLimit` is the documented control for bounding the memory a single `render()` call may allocate (`docs/source/tutorials/dos.md`). Every array-output filter in `src/filters/array.ts` other than `pop` deducts its working set from the limit, so a render that does `{{ huge | shift }}` with `memoryLimit: 100` and `huge.length === 5_000_000` correctly throws `memory alloc limit exceeded`. The identical `{{ huge | pop }}` does **not** throw — the allocation proceeds, and the only ceiling is the Node process's heap. ## Proof of concept ```js const { Liquid } = require('liquidjs'); const l = new Liquid({ memoryLimit: 100 }); // 100-unit budget const huge = Array(5_000_000).fill('x'); // 5M-element context array (async () => { try { await l.parseAndRender('{{ a | shift | size }}', { a: huge }); } catch (e) { console.log('shift: ' + e.message); } // expected: memory alloc limit exceeded try { await l.parseAndRender('{{ a | unshift: 0 | size }}', { a: huge }); } catch (e) { console.log('unshift: ' + e.message); } // expected: memory alloc limit exceeded const out = await l.parseAndRender('{{ a | pop | size }}', { a: huge }); console.log('pop: OK, size=' + out); // size=4999999 — allocation succeeded })(); ``` Observed (against `dist/liquid.node.js` at `a8fd734b5`): ``` shift: memory alloc limit exceeded, line:1, col:1 unshift: memory alloc limit exceeded, line:1, col:1 pop: OK, size=4999999 ``` ## Impact - **`memoryLimit` does not bound `pop` allocations.** Any template that can reach `{{ | pop }}` allocates an

Affected packages

Remediation: Upgrade to 10.27.1 or later.

References

• https://github.com/advisories/GHSA-g357-x5c3-c72p