# CVE-2025-7635: Calix GigaCenter ONT - Unauthenticated Telnet

> Unauthenticated Telnet access allows attackers to gain root privileges on Calix GigaCenter ONT devices.

- **Severity:** High 8.7 (`CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Sep 2025
- **Updated:** 12 Sep 2025
- **Also known as:** GHSA-7rr9-q3x5-6c5c

## What is CVE-2025-7635?

CVE-2025-7635 is a high-severity authentication bypass vulnerability in Calix GigaCenter ONT, published on 9 Sep 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Unauthenticated Telnet access vulnerability in Calix GigaCenter ONT allows root access.This issue affects GigaCenter ONT: 844E, 844G, 844GE, 854GE.

Weakness: CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2025-7635?

It affects 1 product.


Products: Calix Calix Gigacenter Ont.

## How do I fix CVE-2025-7635?

No fix has been published for CVE-2025-7635 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-7635 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-7635 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-7635 and fix it if it is affected.

What it is: CVE-2025-7635 is a high-severity authentication bypass vulnerability in Calix GigaCenter ONT, published on 9 Sep 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-7635 exists.

Affected product: Calix GigaCenter ONT. 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-2025-7635/ (Markdown: https://insights.sbomify.com/CVE-2025-7635/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-7635
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-7635
- OSV: https://osv.dev/vulnerability/CVE-2025-7635

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From sbomify Insights: https://insights.sbomify.com/CVE-2025-7635/
Summaries are generated and may contain mistakes; the official description above is the record.