# CVE-2026-15542: will-moss Isaiah Websocket Connection Authentication main.go improper authentication

> Remote attackers can bypass authentication in the Isaiah web application's websocket connection, potentially gaining unauthorized access.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 13 Jul 2026
- **Updated:** 15 Jul 2026
- **Also known as:** GHSA-9cxj-6mj4-pxvp

## What is CVE-2026-15542?

CVE-2026-15542 is a medium-severity authentication bypass vulnerability in will-moss Isaiah, published on 13 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability has been found in will-moss Isaiah up to 1.36.9. This affects an unknown function of the file app/main.go of the component Websocket Connection Authentication. The manipulation leads to improper authentication. The attack can be initiated remotely. The pull request to fix this issue awaits acceptance.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-15542?


## How do I fix CVE-2026-15542?

No fix has been published for CVE-2026-15542 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-15542 being exploited?

There is no known exploitation of CVE-2026-15542 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-15542 and fix it if it is affected.

What it is: CVE-2026-15542 is a medium-severity authentication bypass vulnerability in will-moss Isaiah, published on 13 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-15542 in the wild and no public exploit code.

Affected product: will-moss Isaiah. 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-2026-15542/ (Markdown: https://insights.sbomify.com/CVE-2026-15542/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-15542
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15542
- OSV: https://osv.dev/vulnerability/CVE-2026-15542

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-15542/
Summaries are generated and may contain mistakes; the official description above is the record.