# CVE-2016-2402: Improper Certificate Validation in OkHttp

> Man-in-the-middle attackers can bypass certificate pinning in OkHttp by presenting a valid chain from a non-pinned trusted CA.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 30 Jan 2017
- **Updated:** 5 Aug 2024
- **Also known as:** CLEANSTART-2026-HM98634, GHSA-4hc2-jh7r-wrc3

## What is CVE-2016-2402?

CVE-2016-2402 is a medium-severity vulnerability in n/a, published on 30 Jan 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

OkHttp before 2.7.4 and 3.x before 3.1.2 allows man-in-the-middle attackers to bypass certificate pinning by sending a certificate chain with a certificate from a non-pinned trusted CA and the pinned certificate.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2016-2402?

4 open source packages ship an affected version, including com.squareup.okhttp3:okhttp. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `com.squareup.okhttp3:okhttp` | Maven | All versions | 2.7.4 |
| `com.squareup.okhttp3:okhttp` | Maven | All versions | 2.7.4 |
| `com.squareup.okhttp3:okhttp` | Maven | From 3.0.0 | 3.1.2 |
| `com.squareup.okhttp3:okhttp` | Maven | From 3.0.0 | 3.1.2 |

Products: Squareup Okhttp, Squareup Okhttp3.

## How do I fix CVE-2016-2402?

Upgrade com.squareup.okhttp3:okhttp to a fixed version for your release line: 2.7.4 or 3.1.2.

## Is CVE-2016-2402 being exploited?

There is no known exploitation of CVE-2016-2402 in the wild and no public exploit code.

Public exploit code:

- Simple script for testing CVE-2016-2402 and similar flaws (github_poc): https://github.com/ikoz/cert-pinning-flaw-poc
- OkHttp sample app vulnerable to CVE-2016-2402 (github_poc): https://github.com/ikoz/certPinningVulnerableOkHttp

## Other vulnerabilities in n/a

- [CVE-2018-20200](https://insights.sbomify.com/CVE-2018-20200/): Security feature bypass in n/a (medium 5.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-2402 and fix it if it is affected.

What it is: CVE-2016-2402 is a medium-severity vulnerability in n/a, published on 30 Jan 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-2016-2402 in the wild and no public exploit code.

Affected packages and fixed versions:
- com.squareup.okhttp3:okhttp (Maven): affected all versions; fixed in 2.7.4
- com.squareup.okhttp3:okhttp (Maven): affected all versions; fixed in 2.7.4
- com.squareup.okhttp3:okhttp (Maven): affected from 3.0.0; fixed in 3.1.2
- com.squareup.okhttp3:okhttp (Maven): affected from 3.0.0; fixed in 3.1.2

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-2016-2402/ (Markdown: https://insights.sbomify.com/CVE-2016-2402/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-2402
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-2402
- OSV: https://osv.dev/vulnerability/CVE-2016-2402

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-2402/
Summaries are generated and may contain mistakes; the official description above is the record.