# CVE-2026-79786: Coroot 1.20.2 through 1.24.5 Unvalidated Redirect URI in MCP OAuth Client Registration

> Attackers can hijack MCP sessions by registering malicious redirect URIs to capture authorization codes from signed-in users.

- **Severity:** High 7.0 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 25 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** GHSA-g3gf-mwj7-2hc4

## What is CVE-2026-79786?

CVE-2026-79786 is a high-severity vulnerability in coroot, published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Coroot's unauthenticated MCP OAuth dynamic client registration endpoint accepts any syntactically valid redirect URI without validation, allowing attackers to register clients pointing to attacker-controlled hosts. Attackers can send authorization URLs to signed-in users, capture their authorization codes upon consent approval, and exchange them for access tokens to hijack MCP sessions.

Weakness: CWE-601 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2026-79786?


## How do I fix CVE-2026-79786?

No fix has been published for CVE-2026-79786 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-79786 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-79786 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-79786 and fix it if it is affected.

What it is: CVE-2026-79786 is a high-severity vulnerability in coroot, published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-79786 exists.

Affected product: coroot. 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-2026-79786/ (Markdown: https://insights.sbomify.com/CVE-2026-79786/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-79786
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-79786
- OSV: https://osv.dev/vulnerability/CVE-2026-79786

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-79786/
Summaries are generated and may contain mistakes; the official description above is the record.