---
title: "CVE-2016-8734\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2016-8734?format=md
keywords: index, follow
---

# CVE-2016-8734

Publication date 30 November 2016

Last updated 25 August 2025

---

Ubuntu priority

**Low**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**6.5 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2016-8734?format=md#impact-score)

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## Description

Apache Subversion's mod\_dontdothat module and HTTP clients 1.4.0 through
1.8.16, and 1.9.0 through 1.9.4 are vulnerable to a denial-of-service
attack caused by exponential XML entity expansion. The attack can cause the
targeted process to consume an excessive amount of CPU resources or memory.

### From the Ubuntu Security Team

Florian Weimer discovered that Subversion clients did not properly
restrict XML entity expansion when accessing http(s):// URLs. A remote
attacker could use this to cause a denial of service.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2016-8734?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| subversion | 21.04 hirsute | Not affected |
| 20.10 groovy | Not affected |
| 20.04 LTS focal | Not affected |
| 19.10 eoan | Not affected |
| 19.04 disco | Not affected |
| 18.10 cosmic | Not affected |
| 18.04 LTS bionic | Not affected |
| 17.10 artful | Not affected |
| 17.04 zesty | Not affected |
| 16.10 yakkety | Ignored end of life |
| 16.04 LTS xenial | Fixed 1.9.3-2ubuntu1.1 |
| 14.04 LTS trusty | Fixed 1.8.8-1ubuntu3.3 |
| 12.04 LTS precise | Ignored end of life |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)
* [Patch details](https://ubuntu.com/security/CVE-2016-8734?format=md#patch-details)

## Notes

---

### [mdeslaur](https://launchpad.net/~mdeslaur)

for mod\_dontdothat, we don't ship it in binary packages
for clients, we build with serf, so we're vulnerable

### Patch details

For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)

| Package | Patch details |
| --- | --- |
| subversion | * Upstream:   <https://subversion.apache.org/security/CVE-2016-8734-advisory.txt> |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

6.5 · Medium

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | Attack complexity | Low |
  | Privileges required | Low |
  | User interaction | None |
  | Scope | Unchanged |
  | Confidentiality impact | None |
  | Integrity impact | None |
  | Availability impact | High |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 6.5 · Medium |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-8734)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2016-8734)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2016-8734)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2016-8734)

### Related Ubuntu Security Notices (USN)

+ [USN-3388-1](https://usn.ubuntu.com/USN-3388-1)
+ Subversion vulnerabilities
+ 11 August 2017

### Other references

* <https://subversion.apache.org/security/CVE-2016-8734-advisory.txt>
* <https://www.cve.org/CVERecord?id=CVE-2016-8734>