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Anthropic Claude extension for Cursor IDE backdoored, impacting thousands

By PulseAugur Editorial · [1 sources] ·

An official Anthropic Claude extension for the Cursor IDE was compromised for nearly 12 hours, potentially affecting up to 5,000 developers. The malicious version of the extension attempted to install a persistent SSH backdoor and steal cloud credentials and API tokens. Cursor has since removed the extension and rotated its marketplace keys, though Anthropic has not yet issued a warning to its users. AI

IMPACT Compromised AI tool extensions can lead to widespread credential theft and system breaches for developers.

RANK_REASON Security vulnerability in a third-party extension for an AI-related tool.

Read on Mastodon — mastodon.social →

AI-generated summary · Google Gemini · from 1 sources. How we write summaries →

Anthropic Claude extension for Cursor IDE backdoored, impacting thousands

How we ranked this

Signal score
8 / 100
Composite score across the factors below. Higher = stronger signal that this story matters right now.
Newsworthiness bucket
Tool
Security vulnerability in a third-party extension for an AI-related tool.
Source corroboration
Single-source cluster
Only one publisher covered this so far. Single-source stories can still rank when the publisher is high-authority, but they lack cross-source corroboration.
Topics
product, safety
Editorial topic classification. Feeds into how the story surfaces on /topic/<slug> hub pages and into the per-entity coverage mix.
AI-industry relevance
High
Clearly on-topic for AI-industry coverage.
Story freshness
Breaking (< 6h)
Fresh story with cross-source coverage still developing. Ranking may shift as more sources report.

Full methodology in our editorial standards.

COVERAGE [1]

  1. Mastodon — mastodon.social TIER_1 English(EN) · [email protected] ·

    An official Anthropic Claude extension for Cursor was backdoored for nearly 12 hours, hitting up to 5,000 developer machines. The malicious build tried to insta

    An official Anthropic Claude extension for Cursor was backdoored for nearly 12 hours, hitting up to 5,000 developer machines. The malicious build tried to install a persistent SSH backdoor and harvest cloud credentials and API tokens. Cursor pulled it and rotated marketplace keys…

    LINKS arstechnica.com/…/anthropic-vs-code-exten… arstechnica.com/…/2026

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