# CVE-2026-15701: Totolink NR1800X lighttpd formLogout.htm Form_Logout stack-based overflow

> A remote attacker can trigger a stack-based buffer overflow in the Totolink NR1800X router's logout function, potentially leading to code execution or denial of service.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Jul 2026
- **Updated:** 15 Jul 2026
- **Also known as:** GHSA-4p43-rxhv-xw72

## What is CVE-2026-15701?

CVE-2026-15701 is a critical memory corruption vulnerability in Totolink NR1800X, published on 14 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A weakness has been identified in Totolink NR1800X 9.1.0u.6279_B20210910. Affected by this issue is the function Form_Logout of the file /formLogout.htm of the component lighttpd. This manipulation of the argument Host causes stack-based buffer overflow. The attack is possible to be carried out remotely. The exploit has been made available to the public and could be used for attacks.

Weakness: CWE-121 (Stack-based Buffer Overflow), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-15701?


## How do I fix CVE-2026-15701?

No fix has been published for CVE-2026-15701 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-15701 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-15701 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-15701 and fix it if it is affected.

What it is: CVE-2026-15701 is a critical memory corruption vulnerability in Totolink NR1800X, published on 14 Jul 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-2026-15701 exists.

Affected product: Totolink NR1800X. 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-2026-15701/ (Markdown: https://insights.sbomify.com/CVE-2026-15701/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-15701
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15701
- OSV: https://osv.dev/vulnerability/CVE-2026-15701

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-15701/
Summaries are generated and may contain mistakes; the official description above is the record.