Regression in Cursor 3.15.6: Remote SSH Extension Host crashes with SIGSEGV on Debian 9 (linux-legacy-x64)

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Hi,

I found what appears to be a regression in Cursor 3.15.6 affecting the linux-legacy-x64 remote server.

Environment

  • Cursor: 3.15.6 Stable
  • Commit: a1f686545fd0ce8917bbd2449f733551a9bce420
  • Client: macOS Apple Silicon

Remote server:

  • Debian 9 (Stretch)
  • glibc 2.24
  • Linux kernel 4.9.0-19-amd64

What happens

The Remote SSH connection succeeds and the remote server starts correctly.

Cursor correctly downloads and starts the new linux-legacy-x64 remote server.

However, the Extension Host crashes after a few seconds with:

Extension Host Process exited with code: null, signal: SIGSEGV

Cursor retries several times, and every Extension Host crashes again with SIGSEGV.

The JSON Language Server errors are only a consequence of the Extension Host crash.

What I tested

Cursor now automatically downloads the linux-legacy-x64 server.

The bundled legacy Node works correctly:

node --version
v20.18.2

I also replaced the bundled Node with a Conda Node 20.20.2.

The behavior is exactly the same.

Therefore, the crash does not appear to be caused by the Node runtime itself.

I also tested the workaround suggested in another forum thread:

export NODE_OPTIONS=“–no-node-snapshot --jitless”

Unfortunately, it does not solve the issue.

Additional information

unprivileged_userns_clone = 0

Cursor correctly falls back to:

Sandbox support detected: false

and continues to start normally, so the sandbox does not appear to be the cause.

Regression

This exact server worked correctly before upgrading to Cursor 3.15.6.

The issue appeared immediately after the update.

I spent several hours debugging this issue. The remote server starts correctly, the bundled legacy Node also starts correctly, and replacing it with another Node version does not change the behavior. The crash consistently occurs when the Remote Extension Host starts.

This issue did not exist before updating to Cursor 3.15.6. No changes were made to the remote server between the last working version and 3.15.6.

Could you please confirm whether this is a known regression affecting the new linux-legacy-x64 build?

If needed, I can provide the complete remoteagent.log and remoteexthost.log, as well as perform additional tests.

Steps to Reproduce

  1. Install Cursor 3.15.6 on macOS.
  2. Connect via Remote SSH to a Debian 9 (Stretch) server (glibc 2.24, kernel 4.9).
  3. Cursor downloads and starts the linux-legacy-x64 remote server.
  4. Wait a few seconds.

Result:
The Remote Extension Host crashes with SIGSEGV and Cursor retries several times before giving up.

Expected Behavior

The Remote Extension Host should remain running and the remote workspace should open normally, as it did before updating to Cursor 3.15.6.

Operating System

MacOS

Version Information

Version: 3.15.6 (Universal)
VS Code Extension API: 1.128.0
Commit: a1f686545fd0ce8917bbd2449f733551a9bce420
Date: 2026-08-06T01:41:03.876Z
Layout: IDE
Build Type: Stable
Release Track: Default
Electron: 40.10.3
Chromium: 144.0.7559.236
Node.js: 24.15.0
V8: 14.4.258.32-electron.0
xterm.js: 6.1.0-beta.291
OS: Darwin arm64 25.5.0

Does this stop you from using Cursor

Yes - Cursor is unusable

5

Hey, thanks for the detailed report. Your diagnosis is spot on. You correctly ruled out the runtime (Conda Node 20.20.2), --no-node-snapshot --jitless, and the sandbox. This isn’t something in your setup.

We reproduced the issue on our side. It affects the linux-legacy-x64 remote server on hosts with older glibc (Debian 9, CentOS 7 / RHEL 7, Amazon Linux 2) after updating the client to 3.15.6. The remote SSH connection and the server itself start fine, but the Remote Extension Host is what crashes, exactly like you described. I’ve passed this to the team.

As a temporary workaround, roll back the client to 3.14.x. With that version, the same legacy remote server works without crashes. You can download the previous version from the changelog: What's New in Cursor — Latest Updates & Release Notes

We don’t need logs (remoteagent.log, remoteexthost.log) for now. The situation is clear. I can’t share an ETA for a fix yet, but I’ll update this thread as soon as I have news.

7

The Cursor 15+ version can establish an SSH connection with Ubuntu 18.04 but cannot use the full IDE functions, such as Git. The remote host keeps restarting constantly. However, the Cursor 14 version has no such issues.

8

This is remoteagent.log in .cursor-server/data/logs

2026-08-12 16:37:08.942 [info]

2026-08-12 16:37:08.965 [info] Extension host agent started.

2026-08-12 16:37:09.206 [info] [127.0.0.1][221c914a][ManagementConnection] New connection established.

2026-08-12 16:37:09.207 [info] [127.0.0.1][a3f27398][ExtensionHostConnection] New connection established.

2026-08-12 16:37:09.240 [info] Getting extensions control

2026-08-12 16:37:09.252 [info] [CursorProclistService] Config enabled feature (subsample every 10s; memoryPressureMonitorEnabled=true)

2026-08-12 16:37:10.878 [info] [127.0.0.1][a3f27398][ExtensionHostConnection] <51954> Launched Extension Host Process.

2026-08-12 16:37:16.378 [info] [127.0.0.1][a3f27398][ExtensionHostConnection] <51954> Extension Host Process exited with code: null, signal: SIGSEGV.

2026-08-12 16:37:16.380 [info] Cancelling previous shutdown timeout

2026-08-12 16:37:16.380 [info] Last EH closed, waiting before shutting down

2026-08-12 16:37:16.425 [error] [127.0.0.1][a3f27398][ExtensionHostConnection] Unknown reconnection token (seen before).

2026-08-12 16:37:16.531 [info] [127.0.0.1][9c7014f8][ExtensionHostConnection] New connection established.

2026-08-12 16:37:16.542 [info] [127.0.0.1][9c7014f8][ExtensionHostConnection] <52656> Launched Extension Host Process.

2026-08-12 16:37:22.358 [info] [127.0.0.1][9c7014f8][ExtensionHostConnection] <52656> Extension Host Process exited with code: null, signal: SIGSEGV.

2026-08-12 16:37:22.359 [info] Cancelling previous shutdown timeout

2026-08-12 16:37:22.359 [info] Last EH closed, waiting before shutting down

2026-08-12 16:37:22.404 [error] [127.0.0.1][9c7014f8][ExtensionHostConnection] Unknown reconnection token (seen before).

2026-08-12 16:37:22.516 [info] [127.0.0.1][8cb4c56f][ExtensionHostConnection] New connection established.

2026-08-12 16:37:22.524 [info] [127.0.0.1][8cb4c56f][ExtensionHostConnection] <53297> Launched Extension Host Process.

2026-08-12 16:37:28.400 [info] [127.0.0.1][8cb4c56f][ExtensionHostConnection] <53297> Extension Host Process exited with code: null, signal: SIGSEGV.

2026-08-12 16:37:28.401 [info] Cancelling previous shutdown timeout

2026-08-12 16:37:28.401 [info] Last EH closed, waiting before shutting down

2026-08-12 16:37:28.436 [error] [127.0.0.1][8cb4c56f][ExtensionHostConnection] Unknown reconnection token (seen before).

2026-08-12 16:38:30.713 [info] [127.0.0.1][221c914a][ManagementConnection] The client has disconnected gracefully, so the connection will be disposed.

2026-08-12 16:39:04.278 [info] [127.0.0.1][acb8a530][ManagementConnection] New connection established.

2026-08-12 16:39:04.338 [info] [127.0.0.1][25ee2651][ExtensionHostConnection] New connection established.

2026-08-12 16:39:04.348 [info] [127.0.0.1][25ee2651][ExtensionHostConnection] <63069> Launched Extension Host Process.

2026-08-12 16:39:05.815 [info] [CursorProclistService] Config enabled feature (subsample every 10s; memoryPressureMonitorEnabled=true)

2026-08-12 16:39:10.344 [info] [127.0.0.1][25ee2651][ExtensionHostConnection] <63069> Extension Host Process exited with code: null, signal: SIGSEGV.

2026-08-12 16:39:10.345 [info] Cancelling previous shutdown timeout

2026-08-12 16:39:10.345 [info] Last EH closed, waiting before shutting down

2026-08-12 16:39:10.431 [error] [127.0.0.1][25ee2651][ExtensionHostConnection] Unknown reconnection token (seen before).

2026-08-12 16:39:10.552 [info] [127.0.0.1][177712e1][ExtensionHostConnection] New connection established.

2026-08-12 16:39:10.561 [info] [127.0.0.1][177712e1][ExtensionHostConnection] <63817> Launched Extension Host Process.

2026-08-12 16:39:16.064 [info] [127.0.0.1][177712e1][ExtensionHostConnection] <63817> Extension Host Process exited with code: null, signal: SIGSEGV.

2026-08-12 16:39:16.064 [info] Cancelling previous shutdown timeout

2026-08-12 16:39:16.065 [info] Last EH closed, waiting before shutting down

2026-08-12 16:39:16.107 [error] [127.0.0.1][177712e1][ExtensionHostConnection] Unknown reconnection token (seen before).

2026-08-12 16:39:16.218 [info] [127.0.0.1][0bf03a87][ExtensionHostConnection] New connection established.

2026-08-12 16:39:16.226 [info] [127.0.0.1][0bf03a87][ExtensionHostConnection] <64326> Launched Extension Host Process.

2026-08-12 16:39:21.815 [info] [127.0.0.1][0bf03a87][ExtensionHostConnection] <64326> Extension Host Process exited with code: null, signal: SIGSEGV.

2026-08-12 16:39:21.815 [info] Cancelling previous shutdown timeout

2026-08-12 16:39:21.816 [info] Last EH closed, waiting before shutting down

2026-08-12 16:39:21.848 [error] [127.0.0.1][0bf03a87][ExtensionHostConnection] Unknown reconnection token (seen before).

I don’t know the reason why the process exited.

9

Hey, thanks for the log. This is the same issue as in the original report in this thread. Ubuntu 18.04 uses the linux-legacy-x64 remote server glibc < 2.28, and on that setup Remote Extension Host crashes with SIGSEGV in 3.15.x. The signature in your log Extension Host Process exited with code: null, signal: SIGSEGV with the restart loop matches exactly. This isn’t caused by anything in your setup.

We’re already tracking this. As a temporary workaround, roll back the client to 3.14.x. On that version, the same legacy remote server works without crashing. You can download the previous version from the changelog: What's New in Cursor — Latest Updates & Release Notes

I can’t share an ETA for the fix yet, but I’ll post in the thread as soon as there’s an update.ф