Cursor’s official notice confirms the affected version, exposure window, payload, impact ceiling, indicators and remediation steps.
Cursor reports a backdoored Claude Code extension in its marketplace
2026-10-29Verified announcementWATCH
Cursor says its marketplace distributed a maliciously modified Anthropic.claude-code 2.1.313 between 2:27 a.m. and 1:35 p.m. PT on October 29. The package attempted to add an SSH key, install persistence and open a reverse tunnel. Cursor says at most 5,000 users were affected, the attacker server is offline and no other extension versions were found altered.
What this means for you
For anyone who installed or updated from the Cursor marketplace during the stated window, uninstalling alone is insufficient because the payload drops persistence. Cursor provides indicators and remediation scripts; credentials accessible from affected hosts should be rotated from a trusted system.
Evidence & related material
Technical details & scores
| Stage | Confirmed incident and remediation notice from Cursor |
|---|---|
| Exposure Window | 2026-10-29 02:27-13:35 PT |
| Scope | Malicious Anthropic.claude-code 2.1.313 from Cursor marketplace; at most 5,000 users |
| Payload | Host inventory, unauthorized SSH key, persistence and attempted reverse SSH tunnel |
| Limit | Cursor says attacker server is offline and found no other altered versions; this does not prove every affected endpoint is clean |
| Time Basis | Official notice provides incident date and PT exposure window; page publication is date-only |
Technical impact 4
Engineering value 5
Adoption signal 3
Maturity 4
Verification cost 1
Risk 5