Tabby automatically confirms ZMODEM protocol detection upon seeing a ZRQINIT header, sending a fixed ZRINIT response directly to the PTY. The injected bytes are consumed by the user's shell as command input. In fish, the leading asterisk triggers glob expansion that can execute a file in a nested directory; in bash or zsh, an OSC 10 escape can provide a command that bypasses PATH resolution. An attacker can supply a crafted file, and the user’s shell runs the embedded commands as root or the user’s effective privileges, achieving arbitrary code execution without any interaction beyond viewing the file. This is a classic CWE‑78 issue of command injection via untrusted input through the terminal.

The vulnerability exists in Tabby (formerly Terminus), a terminal emulator from Eugeny. All versions prior to 1.0.233 are affected; upgrades to 1.0.233 or later contain the fix.

The vulnerability carries a CVSS score of 7, indicating a high risk. EPSS is not reported and the issue is not listed in the CISA KEV catalog, implying low but present exploitation potential. The attack vector is local: an attacker must supply or host a file in the user’s environment, then have the user display it with a command such as cat. No network exploitation or privilege escalation is required beyond running the vulnerable Tabby instance.