# CVE-2016-2181: Denial of service in n/a

> Remote attackers can cause denial of service in OpenSSL DTLS implementations by spoofing records to trigger false-positive packet drops.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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:** Yes
- **Published:** 16 Sep 2016
- **Updated:** 5 Aug 2024
- **Also known as:** ALPINE-CVE-2016-2181, DEBIAN-CVE-2016-2181, GHSA-mpfh-46p6-w5g3, UBUNTU-CVE-2016-2181

## What is CVE-2016-2181?

CVE-2016-2181 is a high-severity denial of service vulnerability in Openssl Openssl, published on 16 Sep 2016. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Anti-Replay feature in the DTLS implementation in OpenSSL before 1.1.0 mishandles early use of a new epoch number in conjunction with a large sequence number, which allows remote attackers to cause a denial of service (false-positive packet drops) via spoofed DTLS records, related to rec_layer_d1.c and ssl3_record.c.

Weakness: CWE-189

## Which versions are affected by CVE-2016-2181?

It affects 2 products.


Products: Openssl Openssl, Oracle Linux.

## How do I fix CVE-2016-2181?

Upgrade to a fixed version.

## Is CVE-2016-2181 being exploited?

There is no known exploitation of CVE-2016-2181 in the wild and no public exploit code.

## Other vulnerabilities in Openssl Openssl

- [CVE-2009-3245](https://insights.sbomify.com/CVE-2009-3245/): Null dereference in n/a (critical 10.0)
- [CVE-2006-3738](https://insights.sbomify.com/CVE-2006-3738/): Memory corruption in n/a (critical 10.0)
- [CVE-2026-63073](https://insights.sbomify.com/CVE-2026-63073/): Untrusted Sender DN Used as Format String in CMP Response Validation (critical 9.8)
- [CVE-2016-6309](https://insights.sbomify.com/CVE-2016-6309/): Use after free in n/a (critical 9.8)
- [CVE-2016-0799](https://insights.sbomify.com/CVE-2016-0799/): Integer overflow in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-2181 and fix it if it is affected.

What it is: CVE-2016-2181 is a high-severity denial of service vulnerability in Openssl Openssl, published on 16 Sep 2016. 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-2016-2181 in the wild and no public exploit code.

Affected product: Openssl Openssl. 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-2016-2181/ (Markdown: https://insights.sbomify.com/CVE-2016-2181/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-2181
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-2181
- OSV: https://osv.dev/vulnerability/CVE-2016-2181

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From sbomify Insights: https://insights.sbomify.com/CVE-2016-2181/
Summaries are generated and may contain mistakes; the official description above is the record.