CVE-2026-102938
mediumpriority · track · 0EPSS 0.001 · 4 %ileDEUSEPSS · scored 2026-10-27
virtualenv is a tool for creating isolated virtual python environments. Prior to 21.7.11, PyEnvCfg.write() writes prompt values verbatim to the line-oriented pyvenv.cfg format while PyEnvCfg._read_values() parses the file with str.splitlines() and accepts the last value for duplicate keys. An attacker who influences --prompt, VIRTUALENV_PROMPT, or configuration input can insert a recognized line boundary and additional keys, including home, causing consumers to use an attacker-selected base interpreter or corrupted environment metadata. The security impact requires prompt input from outside the operator's trust boundary; directly supplied prompt content primarily corrupts the operator's own environment. This issue is fixed in version 21.7.11.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 2–5.8
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (7)
Products and version ranges known to be affected.
- Red Hat Ansible Automation Platform 2.6all versionscert_bundDEcpe:/a:redhat:ansible_automation_platform:2.6
- Red Hat Ansible Automation Platform 2.7all versionscert_bundDEcpe:/a:redhat:ansible_automation_platform:2.7
advisories (4)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-4111Red Hat Ansible Automation Platform: Mehrere SchwachstellenDeutsch2026-10-21csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Red Hat Ansible Automation Platform ausnutzen, um beliebigen Code mit Benutzer- oder Anwendungsrechten auszuführen, gültige kryptografische Token zu fälschen, die Authentifizierung zu umgehen, erweiterte Rechte zu erlangen, Denial-of-Service-Zustände auszulösen sowie Daten zu manipulieren oder offenzulegen.
- GHSA-9h9j-4vrj-gf7gvirtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection2026-09-30ghsa · osvUS
### Summary `pyvenv.cfg` is a line-based format with no escape syntax. `PyEnvCfg.write()` wrote values verbatim, while `PyEnvCfg._read_values()` parses the file with `str.splitlines()`. A value containing a line boundary therefore became additional configuration lines, and because reading is last-wins, the injected keys replaced any key written earlier in the file. ### Impact The `prompt` value is the reachable input: it is set by `--prompt`, by the `VIRTUALENV_PROMPT` environment variable, or from the config file, and `write()` emits `prompt` before `home`. A crafted prompt can therefore set `home` in the generated `pyvenv.cfg`: ```console $ virtualenv --prompt $'x"\nhome = /attacker/path\nprompt = "z' venv $ grep '^home' venv/pyvenv.cfg home = /attacker/path ``` `home` is what tooling reads to locate the base interpreter, so a consumer that trusts it can be pointed elsewhere. `implementation`, `version_info`, `version`, `executable`, `command` and `virtualenv` are also written before `prompt` and can be replaced the same way. This requires the prompt to come from somewhere other than the person running the command, for example a CI job templating a branch name into it, tooling deriving an environment name from user-supplied data, or an inherited `VIRTUALENV_PROMPT`. Where the operator supplies the prompt directly they already control the command line, and the effect is corruption rather than privilege gain: the value is truncated at the boundary and read back with a dangling quote. ### Details The boundary set is the one `str.splitlines()` recognizes, which is wider than `\n`: `\r`, `\v`, `\f`, the file, group and record separators, `U+0085`, `U+2028` and `U+2029` were all written through unchanged and all split the line when read back. ### Patches `PyEnvCfg.write()` now collapses those boundaries to spaces as it serializes each line, so it cannot emit a structurally invalid file regardless of what a caller places in `content`. ### Workarounds Do not pass externally influenced data as the virtualenv prompt. Strip line boundaries from any value before using it as `--prompt` or `VIRTUALENV_PROMPT`.
- BIT-virtualenv-2026-102938virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection2026-10-06vendor · osvUS
virtualenv is a tool for creating isolated virtual python environments. Prior to 21.7.11, PyEnvCfg.write() writes prompt values verbatim to the line-oriented pyvenv.cfg format while PyEnvCfg._read_values() parses the file with str.splitlines() and accepts the last value for duplicate keys. An attacker who influences --prompt, VIRTUALENV_PROMPT, or configuration input can insert a recognized line boundary and additional keys, including home, causing consumers to use an attacker-selected base interpreter or corrupted environment metadata. The security impact requires prompt input from outside the operator's trust boundary; directly supplied prompt content primarily corrupts the operator's own environment. This issue is fixed in version 21.7.11.
- PYSEC-2026-4012virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection2026-09-17vendor · osvUS
`pyvenv.cfg` is a line-based format with no escape syntax. `PyEnvCfg.write()` wrote values verbatim, while `PyEnvCfg._read_values()` parses the file with `str.splitlines()`. A value containing a line boundary therefore became additional configuration lines, and because reading is last-wins, the injected keys replaced any key written earlier in the file. The `prompt` value is the reachable input: it is set by `--prompt`, by the `VIRTUALENV_PROMPT` environment variable, or from the config file, and `write()` emits `prompt` before `home`. A crafted prompt can therefore set `home` in the generated `pyvenv.cfg`. `home` is what tooling reads to locate the base interpreter, so a consumer that trusts it can be pointed elsewhere. `implementation`, `version_info`, `version`, `executable`, `command` and `virtualenv` are also written before `prompt` and can be replaced the same way. This requires the prompt to come from somewhere other than the person running the command, for example a CI job templating a branch name into it, tooling deriving an environment name from user-supplied data, or an inherited `VIRTUALENV_PROMPT`. The boundary set is the one `str.splitlines()` recognizes, which is wider than `\n`: `\r`, `\v`, `\f`, the file, group and record separators, `U+0085`, `U+2028` and `U+2029` were all written through unchanged and all split the line when read back. Fixed in 21.7.11: `PyEnvCfg.write()` now collapses those boundaries to spaces as it serializes each line, so it cannot emit a structurally invalid file regardless of what a caller places in `content`.
also known as (3)
Other names and identifiers for this entity.
- BIT-virtualenv-2026-102938osv
- GHSA-9h9j-4vrj-gf7gosv
- PYSEC-2026-4012osv
sources
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references (4) nvd
External citations — patches, advisories, analysis.
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