# CVE-2026-118772: joi: quadratic-time split in `string().email({ multiple: true })` allows denial of service


- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 29 Oct 2026
- **Updated:** 29 Oct 2026
- **Also known as:** GHSA-4528-x5fx-h6hg

## What is CVE-2026-118772?

CVE-2026-118772 is a high-severity vulnerability in @hapi joi, published on 29 Oct 2026. 

### Official description

joi is a schema description language and data validator for JavaScript. From 17.1.1 until 17.13.9 and 18.3.1, the Joi.string().email({ multiple: true }) rule uses a separator regular expression whose leading whitespace quantifier is retried at every position in a long whitespace run that contains no separator, causing quadratic work during String.prototype.split. The behavior applies to the default separator and every custom separator. Applications that validate attacker-controlled values with the multiple option and no effective prior length limit can have the Node.js event loop blocked for seconds by one request, preventing other work. A .max() rule is not sufficient when abortEarly: false allows the email rule to run after the maximum-length check fails. This vulnerability is fixed in versions 17.13.9 and 18.3.1.

Weakness: CWE-1333 (Inefficient Regular Expression Complexity)

## Which versions are affected by CVE-2026-118772?


## How do I fix CVE-2026-118772?

No fix has been published for CVE-2026-118772 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-118772 being exploited?

There is no known exploitation of CVE-2026-118772 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-118772 and fix it if it is affected.

What it is: CVE-2026-118772 is a high-severity vulnerability in @hapi joi, published on 29 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-118772 in the wild and no public exploit code.

Affected product: @hapi joi. 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-2026-118772/ (Markdown: https://insights.sbomify.com/CVE-2026-118772/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-118772
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-118772
- OSV: https://osv.dev/vulnerability/CVE-2026-118772

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-118772/
Summaries are generated and may contain mistakes; the official description above is the record.