CRITICAL BUG: Memory Leak in Chat/Composer System Causing IDE Crashes

[Sumit_Patil]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Cursor IDE is experiencing severe memory leaks in the chat/composer system that cause the extension host to crash and restart repeatedly. The listener count grows exponentially (180 → 459+ listeners) within minutes, leading to complete IDE instability.
Environment
OS: macOS (darwin 25.0.0)

Workspace: Large PHP codebase (~30,000+ files)
Extensions: Various (but issue persists even with minimal extensions)

Steps to Reproduce

Open Cursor IDE with a large codebase
Use the chat/composer feature for code analysis or file operations
Perform multiple tool calls (file writes, code analysis, etc.)
Monitor the system for 10-30 minutes
IDE will crash and restart

Expected Behavior

Chat/composer should work without memory leaks
Extension host should remain stable
IDE should not crash during normal usage

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.7.23 (Universal)
VSCode Version: 1.99.3
Commit: 5069385c5a69db511722405ab5aeadc01579afd0
Date: 2025-09-30T02:52:09.100Z
Electron: 34.5.8
Chromium: 132.0.6834.210
Node.js: 20.19.1
V8: 13.2.152.41-electron.0
OS: Darwin arm64 25.0.0

For AI issues: which model did you use?

Auto

For AI issues: add Request ID with privacy disabled

Request ID: 208bfa27-b034-478f-a2cf-1b2c19b60341

Additional Information

Timeline of Memory Leak
12:18:10.244 - 180 listeners
12:18:10.249 - 268 listeners (+88 in 5ms)
12:18:10.795 - 274 listeners (+6 in 546ms)
12:20:51.778 - 364 listeners (+90 in 2 minutes)
12:20:53.395 - 459 listeners (+95 in 1.6 seconds)
12:24:54.710 - Extension host terminated unexpectedly
Root Cause Analysis
The issue is in Cursor’s internal chat/composer system, specifically:
Bubble creation system (Pcr.createBubbleFromToolCall)
Tool call processing (w7.submitChatMaybeAbortCurrent)
Code block processing (Tte.processCodeBlocks)
Impact
Critical: IDE becomes unusable due to frequent crashes
Productivity: Work is lost during crashes
Stability: Cannot rely on IDE for development work

Does this stop you from using Cursor

Sometimes - I can sometimes use Cursor

[sanjeed5 (Sanjeed)]

Thanks for this detailed bug report!

Can you please try these:

1. Test in Safe Mode

Run Cursor without extensions to see if the leak persists:

cursor --disable-extensions

2. Check Process Explorer

Open the Process Explorer to see which processes are consuming resources:

• Cmd + Shift + P → Developer: Open Process Explorer
• Look specifically at the extensionHost processes when the listener count starts climbing
• Share a screenshot when you notice the memory leak happening

3. Additional context:

• Which specific chat/composer operations trigger this? (file analysis, code generation, multiple tool calls, etc.)
• Does this happen with a smaller/empty workspace, or only your 30K+ file PHP project?

[Sumit_Patil]

Tested in safe mode, but the IDE still crashes.

Attached is a screenshot of the output when it happened.

Which operations trigger this?

• Code generation using Agent + Auto mode

Does this happen with smaller/empty workspaces, or only with the 30K+ file PHP project?

• It happens only with larger repos. For smaller repos, it works fine.

[sanjeed5 (Sanjeed)]

Thanks for sharing the details, I’ve passed it on to the team.

[oknrd]

I’m running cursor on Ubuntu (22) VM with a large code-base. I was using 1.4x and then upgraded to 1.7.53 and I started noticing that cursor UI freezes suddenly and locks-up the VM. The VM needs to be rebooted by force. Something has gone terribly wrong underneath. What I also observe that when cursor is closed, the RAM consumed does not get freed-up. I updated to 1.7.54, then same problems occur though with a bit less frequency.

Time to lockup after launch is unpredictable. Sometimes it happens in 10 seconds, sometimes in the middle of chat session after couple of minutes.

[cocode (Babak Bandpey)]

VM contra Host machine access rights “can” cause this.

[oknrd]

Has anyone from cursor dev team looking into this?

[Sumit_Patil]

It looks like this issue has been resolved in the latest Cursor release — version 2.0. I haven’t encountered it since updating.