7.1 High

virtualenv: Bash prompt values can change meaning under older compatibility modes

CVE-2026-113723

Summary Caller-supplied prompt text can become executable syntax in the bash activation prompt. An attacker must influence the value passed to virtualenv, and a user must subsequently activate the environment and draw the prompt. Affected area Bash runs with compatibility level 4.2 and draws the environment prompt. Its replacement-string behavior differs from newer compatibility modes, leaving prompt text subject to a second interpretation. The report concerns POSIX activation. It does not establish exposure through unrelated activators. Attacker-controlled input The attacker controls prompt or destination data passed as a virtualenv argument. The user later sources the generated activation script. Affected code The relevant 21.14.8 source is in [bash prompt assembly](https://github.com/pypa/virtualenv/blob/a795ab116356afde11039cf2763d77e8a06da738/src/virtualenv/activation/bash/activate.sh). Mechanism bin/activate copies the prompt into PS1. A shell expands PS1 again when it draws a prompt, so the value must survive both the assignment and that later expansion. The bash and zsh branches escape for their usual prompt rules. Three other paths still interpret prompt data as commands:…

Assessment

CVSS: 7.1 (v4.0)
Severity: High
EPSS: 0.00242% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 23 October 2026
Last updated: 23 October 2026
Affected: pip · virtualenv
Weakness: CWE-78

CVSS vectorCVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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