# CVE-2026-118129: jeremyckahn Chitchatter PostMessage Bootstrap.tsx isConfigMessageEvent improper authentication


- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 27 Oct 2026
- **Updated:** 27 Oct 2026
- **Also known as:** GHSA-4rhf-9gx6-4pqp

## What is CVE-2026-118129?

CVE-2026-118129 is a medium-severity vulnerability in jeremyckahn Chitchatter, published on 27 Oct 2026. 

### Official description

A vulnerability was found in jeremyckahn Chitchatter up to f82538633813c854a81a8b2112a2f6ba17b39cbc. The affected element is the function isConfigMessageEvent of the file src/Bootstrap.tsx of the component PostMessage Handler. Performing a manipulation of the argument parentDomain results in improper authentication. Remote exploitation of the attack is possible. The exploit has been made public and could be used. This product follows a rolling release approach for continuous delivery, so version details for affected or updated releases are not provided. The patch is named e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688. It is recommended to apply a patch to fix this issue. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-118129?


## How do I fix CVE-2026-118129?

No fix has been published for CVE-2026-118129 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-118129 being exploited?

There is no known exploitation of CVE-2026-118129 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-118129 and fix it if it is affected.

What it is: CVE-2026-118129 is a medium-severity vulnerability in jeremyckahn Chitchatter, published on 27 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-118129 in the wild and no public exploit code.

Affected product: jeremyckahn Chitchatter. 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-2026-118129/ (Markdown: https://insights.sbomify.com/CVE-2026-118129/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-118129
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-118129
- OSV: https://osv.dev/vulnerability/CVE-2026-118129

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-118129/
Summaries are generated and may contain mistakes; the official description above is the record.