# CVE-2026-19821: Tenda AC12 httpd web management interface SetSysAutoRebbotCfg formSetRebootTimer buffer overflow

> Remote attackers can trigger a buffer overflow in the Tenda AC12 router's web interface, potentially leading to code execution or service disruption.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/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:** 14 Aug 2026
- **Updated:** 18 Aug 2026
- **Also known as:** GHSA-ch7j-xq25-cfm2

## What is CVE-2026-19821?

CVE-2026-19821 is a high-severity memory corruption vulnerability in Tenda AC12, published on 14 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability was determined in Tenda AC12 15.03.06.23_multi_TD01. This vulnerability affects the function formSetRebootTimer of the file /goform/SetSysAutoRebbotCfg of the component httpd web management interface. This manipulation of the argument rebootTime causes buffer overflow. The attack may be initiated remotely. The exploit has been publicly disclosed and may be utilized.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-19821?


## How do I fix CVE-2026-19821?

No fix has been published for CVE-2026-19821 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-19821 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-19821 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-19821 and fix it if it is affected.

What it is: CVE-2026-19821 is a high-severity memory corruption vulnerability in Tenda AC12, published on 14 Aug 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-2026-19821 exists.

Affected product: Tenda AC12. 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-2026-19821/ (Markdown: https://insights.sbomify.com/CVE-2026-19821/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-19821
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-19821
- OSV: https://osv.dev/vulnerability/CVE-2026-19821

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-19821/
Summaries are generated and may contain mistakes; the official description above is the record.