gchq/CyberChef

bug(Swap Endianness): an uncaught TypeError "u.push is not a function"

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#2,495 opened on Jun 4, 2026

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 (0 comments) (0 reactions) (0 assignees)JavaScript (34,843 stars) (3,944 forks)batch import
buggood first issuehelp wanted

Description

To reproduce that use a direct link https://gchq.github.io/CyberChef/#recipe=Swap_endianness('',2,true)&input=aGVsbG8&oenc=65001&oeol=VT

as you can see an uncaught type error appear like

Swap endianness - TypeError in blob:https://gchq.github.io/ca665e42-4811-40fc-9d6a-a868c6bd8271 on line 2.<br><br>Message: u.push is not a function

the issue simple the first parameter not validated is empty or not

Contributor guide

Tech stack
javascript
Domain
frontend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
1
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
None
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
90
Research direction
Investigate the Swap endianness operation source code to add input validation for the first parameter when it is empty or undefined.