CVE-2026-34430 is a sandbox escape vulnerability in ByteDance Inc.'s DeerFlow product affecting versions prior to commit 92c7a20. The issue arises from an incomplete list of disallowed inputs in the bash tool handling, where regex-based validation can be bypassed using shell features such as directory changes and relative paths. This incomplete shell semantics modeling allows attackers to break out of the sandbox, read and modify files outside the intended boundary, and achieve arbitrary command execution via subprocess invocation with shell interpretation enabled.

Successful exploitation allows unauthenticated attackers to execute arbitrary commands on the host system, read and modify files outside the sandbox, potentially leading to full system compromise. The vulnerability has a high CVSS 4.0 base score of 8.6, indicating significant impact on confidentiality, integrity, and availability.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Until a patch is available, restrict access to vulnerable DeerFlow instances and avoid enabling shell interpretation in subprocess invocations where possible.