A vulnerability was determined in DeepSeek Harness up to 0.2.0-rc.2. This issue affects some unknown processing of the file packages/client/connection/src/browser-auth.ts of the component Browser Auth. This manipulation causes improper authorization. The attack can be initiated remotely. The vendor was contacted early about this disclosure but did not respond in any way.

A vulnerability was found in DeepSeek Harness up to 0.1.0-rc.5. This vulnerability affects the function createContext of the file packages/extensions/cordis-host-runner/src/sandbox.ts. The manipulation results in sandbox issue. It is possible to launch the attack remotely. The vendor was contacted early about this disclosure but did not respond in any way.

An issue in the context-compaction feature of DeepSeek Harness (dsh) commit c291e796 allows attackers to execute a prompt injection attack via crafted external content.

An untrusted search path in DeepSeek Harness (dsh) commit c291e796 allows attackers to execute arbitrary code via supplying and opening crafted executable files in place of legitimate content.

DeepSeek V4 is vulnerable to Incorrect Access Control via a crafted input.

OS Command Injection in internal/gitcmd (git diff filter.clean/smudge invocation) in esengine DeepSeek-Reasonix (Reasonix Studio) allows a local attacker who controls repository content (.gitattributes + .git/config) to execute arbitrary commands via the desktop app's workspace-changes diff viewer.

A security flaw has been discovered in DeepSeek deepseek-harness up to 0.1.7-rc.2. The affected element is the function loadProfile of the file packages/boot/app-boot/src/profile.ts of the component Bundle Patch Handler. The manipulation of the argument dsh.bundle.patch results in path traversal. The attack may be performed from remote. The attack requires a high level of complexity. The exploitability is described as difficult. The exploit has been released to the public and may be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.

DeepSeek Harness before 0.1.2-alpha.1 contains an authentication bypass vulnerability that grants unauthenticated access to its local HTTP agent-control API by accepting a client-supplied loopback Host header in place of validating the actual TCP connection origin. On the default configuration, a confined tool-executed process can reach the loopback API without any port exposure and use it to escape its own OS sandbox, escalate to unconfined execution, and disable the approval prompt. When the port is externally reachable via tunnel, SSH forward, or reverse proxy, a remote attacker can exploit the same flaw to create sessions, execute arbitrary commands, and exfiltrate stored conversation transcripts without credentials.

DeepSeek V3.2 has a Cross Site Scripting (XSS) vulnerability, which allows JavaScript execution through model-generated SVG content.

DeepSeek R1 through V3.1 allows XSS, as demonstrated by JavaScript execution in the context of the run-html-chat.deepseeksvc.com domain. NOTE: some third parties have indicated that this is intended behavior.