# CVE-2026-100740: D-Link DIR-895L L2TP Control Channel tunnel.c tunnel_set_params out-of-bounds write

> Remote attackers can trigger an out-of-bounds write in the L2TP parser of D-Link DIR-895L routers, potentially leading to arbitrary code execution.

- **Severity:** Critical 9.4 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Sep 2026
- **Updated:** 28 Sep 2026
- **Also known as:** GHSA-87gr-9jjp-5f3j

## What is CVE-2026-100740?

CVE-2026-100740 is a critical memory corruption vulnerability in D-Link DIR-895L, published on 27 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability was detected in D-Link DIR-895L A1_102b07. Impacted is the function tunnel_set_params of the file tunnel.c of the component L2TP Control Channel Parser. Performing a manipulation results in out-of-bounds write. The attack may be initiated remotely. The exploit is now public and may be used.

Weakness: CWE-787 (Out-of-bounds Write), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-100740?


## How do I fix CVE-2026-100740?

No fix has been published for CVE-2026-100740 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-100740 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100740 exists.

Public exploit code:

- CVE-2026-100740 PoC: D-Link DIR-895L A1_102b07 L2TP Host Name AVP out-of-bounds write in tunnel_set_params (UDP 1701). Device fingerprint + optional OOB trigger packet for authorized lab testing. https://pocbit.org/pocs/cve-2026-100740 (github_poc): https://github.com/murrez/CVE-2026-100740

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-100740 and fix it if it is affected.

What it is: CVE-2026-100740 is a critical memory corruption vulnerability in D-Link DIR-895L, published on 27 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100740 exists.

Affected product: D-Link DIR-895L. 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-2026-100740/ (Markdown: https://insights.sbomify.com/CVE-2026-100740/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-100740
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-100740
- OSV: https://osv.dev/vulnerability/CVE-2026-100740

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-100740/
Summaries are generated and may contain mistakes; the official description above is the record.