# CVE-2026-28428: Talishar: Authentication Bypass via Empty authKey Parameter Allows Unauthenticated Game Actions

> Unauthenticated attackers can bypass authentication and perform game actions by supplying an empty authKey parameter due to loose comparison logic.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 6 Mar 2026
- **Updated:** 9 Mar 2026
- **Also known as:** GHSA-2659-p579-wv83

## What is CVE-2026-28428?

CVE-2026-28428 is a medium-severity authentication bypass vulnerability in Talishar, published on 6 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Talishar is a fan-made Flesh and Blood project. Prior to commit a9c218e, an authentication bypass vulnerability in Talishar's game endpoint validation logic allows any unauthenticated attacker to perform authenticated game actions — including sending chat messages and submitting game inputs — by supplying an empty authKey parameter (authKey=). The server-side validation uses a loose comparison that accepts an empty string as a valid credential, while correctly rejecting non-empty but incorrect keys. This asymmetry means the authentication mechanism can be completely bypassed without knowing any valid token. This issue has been patched in commit a9c218e.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-28428?

It affects 1 product.


Products: Talishar Talishar.

## How do I fix CVE-2026-28428?

No fix has been published for CVE-2026-28428 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-28428 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-28428 exists.

## Other vulnerabilities in Talishar

- [CVE-2026-28429](https://insights.sbomify.com/CVE-2026-28429/): Talishar: Critical Path Traversal in gameName Parameter (high 7.5)
- [CVE-2026-27632](https://insights.sbomify.com/CVE-2026-27632/): Talishar Vulnerable to Cross-Site Request Forgery (CSRF) (low 2.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-28428 and fix it if it is affected.

What it is: CVE-2026-28428 is a medium-severity authentication bypass vulnerability in Talishar, published on 6 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-28428 exists.

Affected product: Talishar. 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-2026-28428/ (Markdown: https://insights.sbomify.com/CVE-2026-28428/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-28428
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28428
- OSV: https://osv.dev/vulnerability/CVE-2026-28428

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-28428/
Summaries are generated and may contain mistakes; the official description above is the record.