> Yesterday, Anthropic were compromised and Cursor extension used by tens of millions of developers for Claude access was delivering a remote access trojan via an SSH reverse backdoor
That's a bit hyperbolic: someone released a version of the Claude Code VS Code extension with a backdoor on the Cursor marketplace:
> a maliciously modified version of Anthropic’s Claude Code extension was made available in the Cursor VS Code extension Marketplace
Cursor does a bad reporting branding OpenVSX as "Cursor Marketplace". What
a joke the company had become under Elon. But also it might be related to
Anthropic/SpaceX business ties, they try to minimize damage on Anthropic
pre-IPO
Cursor always used OpenVSX for VSCode extensions. There is separate "Cursor Marketplace" (https://cursor.com/marketplace) but it installs "Cursor Plugins" which are exclusively Cursor feature not related to VSCode, and Anthropic had never released a "Cursor Plugin"
It's part of the plan to make you believe it is not as performant as what their flesh puppets pretend it to be. All these people in AI companies shown all the time on the web, did you ever met one?
The matrix has you Andrew.
I know, I should have launched a career in conspirationism.
Cursor uses OpenVSX marketplace (https://open-vsx.org/), that all non-Microsoft forks of VSCode utilize
(official marketplace is only allowed in official proprietary VSCode release). It's not really related to Cursor/SpaceX in any way.
I suspect it's still Anthropic who were hacked, because they control OpenVSX
account with release privileges.
The affected Open VSX extension is owned by Anthropic employee Igor Kofman, but it is unclear whether his account or another part of the publishing process was compromised.
Yeah OpenVSX security is a joke, they also have dumb search algorithm which
allows for easy squatting of similar-looking extension names so they show up in search first when you look for official extensions. There were quite a few prominent hacks done that way. I think Microsoft likes OpenVSX situation because it allows them to claim
their proprietary VSCode marketplace to be more secure.
There is no alternative really. Cursor was the market leader in LLM-assisted IDE experience before SpaceX acquisition (though Elon nerfed the product a lot in recent months). And there is still no
good alternative on a market. Google tries to compete via Antigravity, but that also uses OpenVSX. I myself use Cursor and use Claude there installed via OpenVSX, and was not affected only thanks to my laziness (I saw upgrade button, but became distracted and did not click). I hope this situation will become a trigger to improve OpenVSX security.
Sort of hoping it's Anthropic and their specific OpenVSX account credentials. As opposed to the worse case of an OpenVSX flaw that's broader. A ton of AI-enabled IDEs are VsCodium forks pointed at OpenVSX...Cursor, Anti Gravity, Kiro, Trae, Devin, etc.
Version 2.1.313 is missing from the official Claude Code GitHub repo's CHANGELOG[0]. There's also no tag[1] for 2.1.313[1], but 2.1.312[2], and 2.1.314[3] exist.
You’re likely right, but they also might’ve just pulled the version (number) everywhere to make it ‘clearer’ or out of ‘caution’.
Is there any industry standard about if a compromised version is distributed via one channel, the owner does or doesn’t drop/bump that same version on unaffected channels too?
My question here - does this effect those of us using the official vscode/vscode marketplace? It would seem to imply this was specific to cursor's marketplace but it would be good to know regardless
A malicious version of Anthropic’s Claude Code VS Code extension, version 2.1.313, was published to the Open VSX registry on Oct. 30. According to ChainCatcher, security researcher Paul McCarty, known as 6mile, described the finding in a post on the OpenSource Malware blog. Researchers confirmed the analyzed Open VSX release was malicious and submitted a threat report about the same version on Microsoft’s VS Code Marketplace as a precaution.
If the sole purpose of this hack was to steal cryptocurrency, a silver lining might be, as in many similar cases, that if you stay away from that particular dumpster fire you are probably okay. I mean there's still a reverse shell on your machine to fix, but at least nothing of value was lost.
> Today we identified a security incident involving a specific extension package in the Cursor VS Code extension Marketplace: Anthropic.claude-code version 2.1.313. This malicious version of the extension was not developed by Anthropic. At most 5,000 users were affected, and we will reach out directly.
I mean, the title seems misleading at best. 3rd party extension, the kind you should not trust unless signed by somebody you trust.
Its sort of like having a sysadmin constantly watching. Poking through logs pcaps & monitoring for unusual activities.
Also works with local models well enough.
What appears to be an official Binance account reporting it also:
https://www.binance.com/en/square/post/10-30-2026-claude-cod...
That's a bit hyperbolic: someone released a version of the Claude Code VS Code extension with a backdoor on the Cursor marketplace:
> a maliciously modified version of Anthropic’s Claude Code extension was made available in the Cursor VS Code extension Marketplace
https://cursor.com/blog/claude-code-extension-security-notic...
Cursor does a bad reporting branding OpenVSX as "Cursor Marketplace". What a joke the company had become under Elon. But also it might be related to Anthropic/SpaceX business ties, they try to minimize damage on Anthropic pre-IPO
The matrix has you Andrew.
I know, I should have launched a career in conspirationism.
I suspect it's still Anthropic who were hacked, because they control OpenVSX account with release privileges.
edit:
Binance confirms my suspicions, via https://www.binance.com/en/square/post/10-30-2026-claude-cod...
This could have been avoided by having extensions signed by company doing them with keys and review
Binance got a pretty expensive lesson if that was the cause for their recent hack
Version 2.1.313 is missing from the official Claude Code GitHub repo's CHANGELOG[0]. There's also no tag[1] for 2.1.313[1], but 2.1.312[2], and 2.1.314[3] exist.
0: https://github.com/anthropics/claude-code/blob/main/CHANGELO...
1: https://github.com/anthropics/claude-code/releases/tag/v2.1....
2: https://github.com/anthropics/claude-code/releases/tag/v2.1....
3: https://github.com/anthropics/claude-code/releases/tag/v2.1....
Is there any industry standard about if a compromised version is distributed via one channel, the owner does or doesn’t drop/bump that same version on unaffected channels too?
I don't use Cursor or the VSCode extension, but know plenty in our organisation who use the latter. How worried should we be?
A malicious version of Anthropic’s Claude Code VS Code extension, version 2.1.313, was published to the Open VSX registry on Oct. 30. According to ChainCatcher, security researcher Paul McCarty, known as 6mile, described the finding in a post on the OpenSource Malware blog. Researchers confirmed the analyzed Open VSX release was malicious and submitted a threat report about the same version on Microsoft’s VS Code Marketplace as a precaution.
/s
I've started developing with a separate user account to limit the blast radius but you still need to login to access repos and use AI features.
This is fine.
I mean, the title seems misleading at best. 3rd party extension, the kind you should not trust unless signed by somebody you trust.