fish-shell: Uncontrolled Search Path Element
CVE-2022-20001 is a high-severity uncontrolled search path element vulnerability in fish-shell, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected fish-shell versions: >= 3.1.0, < 3.4.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.48% chance of exploitation within 30 days, higher than 74% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of fish-shell you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Fish-shell | fish-shell | >= 3.1.0, < 3.4.0 | Not stated |
| Fishshell | Fish | 3.1.0 through 3.3.1 | Not stated |
| Fedora Project | Fedora | 35; 36 | Not stated |
| Debian | Debian Linux | 11.0 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA (github.com) |
| CVSS 3.1 | 7.8 | High | NVD |
| CVSS 2.0 | 6.8 | Medium | NVD |
Official description
fish is a command line shell. fish version 3.1.0 through version 3.3.1 is vulnerable to arbitrary code execution. git repositories can contain per-repository configuration that change the behavior of git, including running arbitrary commands. When using the default configuration of fish, changing to a directory automatically runs `git` commands in order to display information about the current repository in the prompt. If an attacker can convince a user to change their current directory into one controlled by the attacker, such as on a shared file system or extracted archive, fish will run arbitrary commands under the attacker's control. This problem has been fixed in fish 3.4.0. Note that running git in these directories, including using the git tab completion, remains a potential trigger for this issue. As a workaround, remove the `fish_git_prompt` function from the prompt.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Uncontrolled Search Path Element
The product uses a fixed or controlled search path to find resources, but one or more locations in that path can be under the control of unintended actors.
How developers prevent this class of flaw
- Hard-code the search path to a set of known-safe values (such as system directories), or only allow them to be specified by the administrator in a configuration file. Do not allow these settings to be modified by an external party. Be careful to avoid related weaknesses such as CWE-426 and CWE-428.
- When invoking other programs, specify those programs using fully-qualified pathnames. While this is an effective approach, code that uses fully-qualified pathnames might not be portable to other systems that do not use the same pathnames. The portability can be improved by locating the full-qualified paths in a centralized, easily-modifiable location within the source code, and having the code refer to these paths.
- Remove or restrict all environment settings before invoking other programs. This includes the PATH environment variable, LD_LIBRARY_PATH, and other settings that identify the location of code libraries, and any application-specific search paths.
More Uncontrolled Search Path Element vulnerabilities (CWE-427)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/fish-shell/fish-shell/security/advisories/GHSA-pj5f-6vxj-f5mqThird Party Advisory
Patches and release notes
- github.com/fish-shell/fish-shell/pull/8589Third Party Advisory
- github.com/fish-shell/fish-shell/releases/tag/3.4.0Release Notes, Third Party Advisory
Third-party and government advisories
- debian.org/security/2022/dsa-5234Third Party Advisory
Other references
Recent Uncontrolled Search Path Element vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.0 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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