# CVE-2026-111172: @casl/ability 6.7.5 before 7.0.2 Prototype Pollution via rulesToFields setByPath

> Attackers can cause denial of service in Node.js applications by exploiting prototype pollution in the @casl/ability library via crafted rule conditions.

- **Severity:** Medium 6.0 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Oct 2026
- **Updated:** 16 Oct 2026
- **Also known as:** GHSA-6vwj-298m-4jg8

## What is CVE-2026-111172?

CVE-2026-111172 is a medium-severity vulnerability in stalniy @casl/ability, published on 15 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

@casl/ability 6.7.5 before 7.0.2 contains a prototype pollution vulnerability in rulesToFields() that allows attackers to modify inherited builtins via dotted condition keys. Attackers controlling rule conditions can supply keys like 'toString.call' to alter shared builtin functions process-wide, causing denial of service for the Node.js process.

Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2026-111172?


## How do I fix CVE-2026-111172?

No fix has been published for CVE-2026-111172 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-111172 being exploited?

There is no known exploitation of CVE-2026-111172 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-111172 and fix it if it is affected.

What it is: CVE-2026-111172 is a medium-severity vulnerability in stalniy @casl/ability, published on 15 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-111172 in the wild and no public exploit code.

Affected product: stalniy @casl/ability. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-111172/ (Markdown: https://insights.sbomify.com/CVE-2026-111172/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-111172
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-111172
- OSV: https://osv.dev/vulnerability/CVE-2026-111172

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-111172/
Summaries are generated and may contain mistakes; the official description above is the record.