# CVE-2026-119756: Tasmota 16.0.0 Heap Out-of-Bounds Write via Device Groups UDP


- **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`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 9 Nov 2026
- **Updated:** 9 Nov 2026
- **Also known as:** GHSA-6g2f-6p9p-vvm8

## What is CVE-2026-119756?

CVE-2026-119756 is a critical vulnerability in arendst Tasmota, published on 9 Nov 2026. 

### Official description

Tasmota through 16.0.0, fixed in commit e97e1e4, contains a heap out-of-bounds write vulnerability in SendReceiveDeviceGroupMessage() that allows unauthenticated attackers on the local network to corrupt heap memory by sending crafted Device Groups messages over UDP port 4447 that cause the log_remaining counter to go negative and writes to exceed the fixed 512-byte buffer. Attackers can exploit this flaw to crash the device or potentially achieve native code execution on ESP8266 and ESP32 platforms that lack ASLR and heap cookies.

Weakness: CWE-805 (Buffer Access with Incorrect Length Value)

## Which versions are affected by CVE-2026-119756?


## How do I fix CVE-2026-119756?

No fix has been published for CVE-2026-119756 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-119756 being exploited?

There is no known exploitation of CVE-2026-119756 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-119756 and fix it if it is affected.

What it is: CVE-2026-119756 is a critical vulnerability in arendst Tasmota, published on 9 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-119756 in the wild and no public exploit code.

Affected product: arendst Tasmota. 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-2026-119756/ (Markdown: https://insights.sbomify.com/CVE-2026-119756/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-119756
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-119756
- OSV: https://osv.dev/vulnerability/CVE-2026-119756

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-119756/
Summaries are generated and may contain mistakes; the official description above is the record.