# CVE-2013-2099: Denial of service in n/a

> Remote attackers can cause denial of service via CPU exhaustion by exploiting algorithmic complexity in Python's SSL hostname matching function.

- **Severity:** Medium 4.3 (`AV:N/AC:M/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:** Yes
- **Published:** 9 Oct 2013
- **Updated:** 6 Aug 2024
- **Also known as:** CVE-2013-2098, DEBIAN-CVE-2013-2099, GHSA-cqcg-qrcv-vr6v, PSF-2013-1, RHSA-2014:1263, RHSA-2014:1690, RHSA-2015:0042, UBUNTU-CVE-2013-2099

## What is CVE-2013-2099?

CVE-2013-2099 is a medium-severity denial of service vulnerability in Canonical Ubuntu Linux, published on 9 Oct 2013. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Algorithmic complexity vulnerability in the ssl.match_hostname function in Python 3.2.x, 3.3.x, and earlier, and unspecified versions of python-backports-ssl_match_hostname as used for older Python versions, allows remote attackers to cause a denial of service (CPU consumption) via multiple wildcard characters in the common name in a certificate.

Weakness: CWE-399

## Which versions are affected by CVE-2013-2099?

It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `python-backports-ssl_match_hostname` | Red Hat:openstack:4::el6 | All versions | 0:3.4.0.2-1.el6 |
| `cloud-init` | Red Hat:rhel_common:6::el6 | All versions | 0:0.7.5-1.el6 |
| `python-backports` | Red Hat:rhel_common:6::el6 | All versions | 0:1.0-3.el6 |
| `python-backports-ssl_match_hostname` | Red Hat:rhel_common:6::el6 | All versions | 0:3.4.0.2-1.el6 |
| `python-boto` | Red Hat:rhel_common:6::el6 | All versions | 0:2.25.0-2.el6 |
| `python-jsonpatch` | Red Hat:rhel_common:6::el6 | All versions | 0:1.2-2.el6 |
| `python-jsonpointer` | Red Hat:rhel_common:6::el6 | All versions | 0:1.0-2.el6 |
| `python-six` | Red Hat:rhel_common:6::el6 | All versions | 0:1.6.1-1.el6 |
| `python-urllib3` | Red Hat:rhel_common:6::el6 | All versions | 0:1.5-5.1.2.el6 |
| `rhsc` | Red Hat:storage:2.1:console:el6 | All versions | 0:2.1.2-0.40.el6rhs |
| `rhsc-backend` | Red Hat:storage:2.1:console:el6 | All versions | 0:2.1.2-0.40.el6rhs |
| `rhsc-branding-rhs` | Red Hat:storage:2.1:console:el6 | All versions | 0:2.1.5-2.0.el6rhs |
| `rhsc-dbscripts` | Red Hat:storage:2.1:console:el6 | All versions | 0:2.1.2-0.40.el6rhs |
| `rhsc-lib` | Red Hat:storage:2.1:console:el6 | All versions | 0:2.1.2-0.40.el6rhs |
| `rhsc-restapi` | Red Hat:storage:2.1:console:el6 | All versions | 0:2.1.2-0.40.el6rhs |
| `rhsc-setup` | Red Hat:storage:2.1:console:el6 | All versions | 0:2.1.2-0.40.el6rhs |
| `rhsc-tools` | Red Hat:storage:2.1:console:el6 | All versions | 0:2.1.2-0.40.el6rhs |
| `rhsc-webadmin-portal` | Red Hat:storage:2.1:console:el6 | All versions | 0:2.1.2-0.40.el6rhs |
| `glusterfs` | Red Hat:storage:2.1:server:el6 | All versions | 0:3.4.0.68rhs-1.el6rhs |
| `glusterfs-api` | Red Hat:storage:2.1:server:el6 | All versions | 0:3.4.0.68rhs-1.el6rhs |
| `glusterfs-api-devel` | Red Hat:storage:2.1:server:el6 | All versions | 0:3.4.0.68rhs-1.el6rhs |
| `glusterfs-debuginfo` | Red Hat:storage:2.1:server:el6 | All versions | 0:3.4.0.68rhs-1.el6rhs |
| `glusterfs-devel` | Red Hat:storage:2.1:server:el6 | All versions | 0:3.4.0.68rhs-1.el6rhs |
| `glusterfs-fuse` | Red Hat:storage:2.1:server:el6 | All versions | 0:3.4.0.68rhs-1.el6rhs |
| `glusterfs-geo-replication` | Red Hat:storage:2.1:server:el6 | All versions | 0:3.4.0.68rhs-1.el6rhs |
| `glusterfs-libs` | Red Hat:storage:2.1:server:el6 | All versions | 0:3.4.0.68rhs-1.el6rhs |
| `glusterfs-rdma` | Red Hat:storage:2.1:server:el6 | All versions | 0:3.4.0.68rhs-1.el6rhs |
| `glusterfs-server` | Red Hat:storage:2.1:server:el6 | All versions | 0:3.4.0.68rhs-1.el6rhs |
| `python-backports` | Red Hat:storage:2.1:server:el6 | All versions | 0:1.0-3.el6 |
| `python-backports-ssl_match_hostname` | Red Hat:storage:2.1:server:el6 | All versions | 0:3.4.0.2-1.el6 |
| `redhat-storage-server` | Red Hat:storage:2.1:server:el6 | All versions | 0:2.1.4.2-1.el6rhs |
| `glusterfs` | Red Hat:storage:2:client:el5 | All versions | 0:3.4.0.68rhs-1.el5 |
| `glusterfs-api` | Red Hat:storage:2:client:el5 | All versions | 0:3.4.0.68rhs-1.el5 |
| `glusterfs-api-devel` | Red Hat:storage:2:client:el5 | All versions | 0:3.4.0.68rhs-1.el5 |
| `glusterfs-debuginfo` | Red Hat:storage:2:client:el5 | All versions | 0:3.4.0.68rhs-1.el5 |
| `glusterfs-devel` | Red Hat:storage:2:client:el5 | All versions | 0:3.4.0.68rhs-1.el5 |
| `glusterfs-fuse` | Red Hat:storage:2:client:el5 | All versions | 0:3.4.0.68rhs-1.el5 |
| `glusterfs-libs` | Red Hat:storage:2:client:el5 | All versions | 0:3.4.0.68rhs-1.el5 |
| `glusterfs-rdma` | Red Hat:storage:2:client:el5 | All versions | 0:3.4.0.68rhs-1.el5 |
| `glusterfs` | Red Hat:storage:3:client:el6 | All versions | 0:3.4.0.68rhs-1.el6 |

Products: Canonical Ubuntu Linux, Python Python.

## How do I fix CVE-2013-2099?

Apply the vendor's patch.

## Is CVE-2013-2099 being exploited?

There is no known exploitation of CVE-2013-2099 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2013-2099 and fix it if it is affected.

What it is: CVE-2013-2099 is a medium-severity denial of service vulnerability in Canonical Ubuntu Linux, published on 9 Oct 2013. 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-2013-2099 in the wild and no public exploit code.

Affected product: Canonical Ubuntu Linux. 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-2013-2099/ (Markdown: https://insights.sbomify.com/CVE-2013-2099/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2013-2099
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2013-2099
- OSV: https://osv.dev/vulnerability/CVE-2013-2099

---
From sbomify Insights: https://insights.sbomify.com/CVE-2013-2099/
Summaries are generated and may contain mistakes; the official description above is the record.