# CVE-2016-7835: Use after free in H2O

> Remote attackers can trigger a use-after-free in H2O to cause denial of service or steal server certificate private keys.

- **Severity:** Critical 9.1 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Jun 2017
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-p8m4-qhm5-5gm6

## What is CVE-2016-7835?

CVE-2016-7835 is a critical use after free vulnerability in Kazuho Oku H2O, published on 9 Jun 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Use-after-free vulnerability in H2O allows remote attackers to cause a denial-of-service (DoS) or obtain server certificate private keys and possibly other information.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2016-7835?

It affects 2 products.


Products: Dena H2o, H2o Project H2o.

## How do I fix CVE-2016-7835?

No fix has been published for CVE-2016-7835 yet. Limit exposure of the affected software until one is available.

## Is CVE-2016-7835 being exploited?

There is no known exploitation of CVE-2016-7835 in the wild and no public exploit code.

## Other vulnerabilities in Kazuho Oku H2O

- [CVE-2018-0608](https://insights.sbomify.com/CVE-2018-0608/): Memory corruption in H2O (critical 9.8)
- [CVE-2023-30847](https://insights.sbomify.com/CVE-2023-30847/): H2O vulnerable to read from uninitialized pointer in the reverse proxy handler (high 8.2)
- [CVE-2017-10868](https://insights.sbomify.com/CVE-2017-10868/): Denial of service in H2O (high 7.5)
- [CVE-2017-10869](https://insights.sbomify.com/CVE-2017-10869/): Memory corruption in H2O (high 7.5)
- [CVE-2017-10908](https://insights.sbomify.com/CVE-2017-10908/): Denial of service in H2O (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-7835 and fix it if it is affected.

What it is: CVE-2016-7835 is a critical use after free vulnerability in Kazuho Oku H2O, published on 9 Jun 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2016-7835 in the wild and no public exploit code.

Affected product: Kazuho Oku H2O. 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-2016-7835/ (Markdown: https://insights.sbomify.com/CVE-2016-7835/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-7835
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-7835
- OSV: https://osv.dev/vulnerability/CVE-2016-7835

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-7835/
Summaries are generated and may contain mistakes; the official description above is the record.