CVE-2026-113732: Hatch · virtualenv activate.fish runs commands from a path or prompt with a backslash before a quote
Affects hatchSource GCVE Database
Not known to be exploited · CVSS 7.8 High : upgrade to 1.18.1_1 or 1.6.2 soon.
Data as of 27 Oct 2026, 23:13 UTC
- Patch
- Available – fixed in 1.18.1_1, 1.6.2
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 20 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade hatch to 1.18.1_1 or 1.6.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Homebrewhatchpkg:brew/hatchOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
### Impact `FishActivator` defines no `quote()`, so it inherits `ViaTemplateActivator.quote`, which returns `shlex.quote(string)`. That function follows POSIX `sh` rules, where a backslash inside single quotes stays a literal character. fish reads `\'` inside single quotes as an escaped quote and `\\` as an escaped backslash. A value with a backslash before a quote therefore ends the literal somewhere other than where `shlex.quote` put the end, and fish expands the command substitution that follows. The environment path reaches `set -gx VIRTUAL_ENV`, and `--prompt` or `VIRTUALENV_PROMPT` reaches `set -gx VIRTUAL_ENV_PROMPT`. For `--prompt "x\'\$(touch PWNED)'\'"`, the generated `activate.fish` contains: ```fish set -gx VIRTUAL_ENV_PROMPT 'x\'"'"'$(touch PWNED)'"'"'\'"'"'' ``` `source bin/activate.fish` runs `touch PWNED`, and fish prints no error. The same payload as a directory name runs through `VIRTUAL_ENV`. `--prompt .` takes the current directory's name, so running virtualenv inside a directory someone else named is enough. Without the backslash the payload runs nothing, and under bash it runs nothing either. virtualenv generates `activate.fish` by default. An attacker needs to influence the environment path or prompt: a CI job or wrapper tool that passes a branch, project or job name through, or a directory in a cloned repository or unpacked archive. The bug affects every release up to 21.14.1 that ships `activate.fish`. The GHSA-p58f-9548-mpm2 fix in 21.7.13 moved the placeholders outside their quotes but kept `shlex.quote`. ### Patches Fixed in 21.14.2. `activate.fish` now escapes backslashes and single quotes the way fish reads them, so the example above runs nothing and shows the prompt as given. Fix: https://github.com/pypa/virtualenv/commit/3bddeaf8d02c3ee7f576503efb082f8f494cfcab ### Workarounds Do not create an environment whose path or prompt contains a backslash, and inspect `activate.fish` before you source one you did not create. ### Credits Kevin Stubbings (@Kwstubbs) of GitHub Security Lab reported this issue.
References
- github.com/pypa/virtualenv/security/advisories/GHSA-c947-3pg5-gm8q (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-113732 (opens in a new tab)
- github.com/pypa/virtualenv/commit/3bddeaf8d02c3ee7f576503efb082f8f494cfcab (opens in a new tab)
- github.com/pypa/virtualenv (opens in a new tab)
- github.com/pypa/virtualenv/releases/tag/21.14.2 (opens in a new tab)