# CVE-2011-1473: Denial of service in n/a

> Remote attackers can cause denial of service via CPU exhaustion by exploiting improper restrictions on client-initiated SSL/TLS renegotiations in OpenSSL.

- **Severity:** Medium 5.0 (`AV:N/AC:L/Au:N/C:N/I:N/A:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Jun 2012
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-5wj2-7gqw-v6cm

## What is CVE-2011-1473?

CVE-2011-1473 is a medium-severity denial of service vulnerability in Openssl Openssl, published on 16 Jun 2012. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

OpenSSL before 0.9.8l, and 0.9.8m through 1.x, does not properly restrict client-initiated renegotiation within the SSL and TLS protocols, which might make it easier for remote attackers to cause a denial of service (CPU consumption) by performing many renegotiations within a single connection, a different vulnerability than CVE-2011-5094.  NOTE: it can also be argued that it is the responsibility of server deployments, not a security library, to prevent or limit renegotiation when it is inappropriate within a specific environment

Weakness: CWE-264

## Which versions are affected by CVE-2011-1473?

It affects 1 product.


Products: Openssl Openssl.

## How do I fix CVE-2011-1473?

No fix has been published for CVE-2011-1473 yet. Limit exposure of the affected software until one is available.

## Is CVE-2011-1473 being exploited?

There is no known exploitation of CVE-2011-1473 in the wild and no public exploit code.

Public exploit code:

- A bash script that attempts to flood a server with TLS renegotiations by using the openssl client.  See CVE-2011-1473 and CVE-2011-1473 for details. (github_poc): https://github.com/XDLDCG/bash-tls-reneg-attack
- https://github.com/zjt674449039/cve-2011-1473 (github_poc): https://github.com/zjt674449039/cve-2011-1473
- CVE-2011-1473 POC script (github_poc): https://github.com/khaledibnalwalid/CVE-2011-1473-POC

## 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-2011-1473 and fix it if it is affected.

What it is: CVE-2011-1473 is a medium-severity denial of service vulnerability in Openssl Openssl, published on 16 Jun 2012. 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-2011-1473 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-2011-1473/ (Markdown: https://insights.sbomify.com/CVE-2011-1473/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2011-1473
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2011-1473
- OSV: https://osv.dev/vulnerability/CVE-2011-1473

---
From sbomify Insights: https://insights.sbomify.com/CVE-2011-1473/
Summaries are generated and may contain mistakes; the official description above is the record.