A flaw in DeepSeek Harness, DeepSeek's open-source tool for running AI coding agents on a developer's machine, let a sandboxed agent turn off its own sandbox with a single command.
The tool runs an agent's commands inside an operating-system sandbox, so that an agent working on untrusted files cannot write outside its workspace. The agent could remove that limit by calling the tool's own web interface on the same machine, and its commands would then run outside the sandbox without an approval prompt.
It worked on a default installation until DeepSeek fixed the tool on August 27, and it required attacker-supplied text that the agent read to prompt it to make the call.
The flaw is tracked as CVE-2026-82533. VulnCheck, which assigned the identifier, published the record on September 8 and rated the flaw 9.4 out of 10.
OX Research, the security firm that reported the flaw, said one shell command was enough. The command invoked the tool's local interface and set the agent's session to a mode called danger-full-access, which turns off the sandbox and stops approval prompts.
