The vulnerability is in the context-compaction feature of DeepSeek Harness (dsh), commit c291e796. By supplying crafted external content, an attacker can force the system to inject malicious instructions into the prompt, enabling arbitrary code to be executed under the application’s context. This exploit allows attackers to bypass normal input constraints and potentially take control of the environment running the harness.

DeepSeek Harness (dsh) is affected when it includes the context-compaction implementation from commit c291e796. No specific version is listed, but any installation that incorporates that commit is vulnerable.

The exploit is remotely triggered through externally supplied content and can be carried out without prior authentication. While an EPSS score is unavailable and the vulnerability is not yet in the CISA KEV catalog, the potential for remote code execution signifies a high severity. The exact CVSS score is not provided, but the nature of the flaw suggests a serious risk if the feature is enabled in an exposed environment.