---
title: "CVE-2017-7805\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-2017-7805?format=md
keywords: index, follow
---

# CVE-2017-7805

Publication date 29 September 2017

Last updated 25 August 2025

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**7.5 · High**

[Score breakdown](https://ubuntu.com/security/CVE-2017-7805?format=md#impact-score)

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## Description

During TLS 1.2 exchanges, handshake hashes are generated which point to a
message buffer. This saved data is used for later messages but in some
cases, the handshake transcript can exceed the space available in the
current buffer, causing the allocation of a new buffer. This leaves a
pointer pointing to the old, freed buffer, resulting in a use-after-free
when handshake hashes are then calculated afterwards. This can result in a
potentially exploitable crash. This vulnerability affects Firefox < 56,
Firefox ESR < 52.4, and Thunderbird < 52.4.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| firefox | 18.10 cosmic | Fixed 56.0+build6-0ubuntu1 |
| 18.04 LTS bionic | Fixed 56.0+build6-0ubuntu1 |
| 17.10 artful | Fixed 56.0+build6-0ubuntu1 |
| 17.04 zesty | Fixed 56.0+build6-0ubuntu0.17.04.1 |
| 16.04 LTS xenial | Fixed 56.0+build6-0ubuntu0.16.04.1 |
| 14.04 LTS trusty | Fixed 56.0+build6-0ubuntu0.14.04.1 |
| nss | 18.10 cosmic | Fixed 2:3.32-1ubuntu3 |
| 18.04 LTS bionic | Fixed 2:3.32-1ubuntu3 |
| 17.10 artful | Fixed 2:3.32-1ubuntu3 |
| 17.04 zesty | Fixed 2:3.28.4-0ubuntu0.17.04.3 |
| 16.04 LTS xenial | Fixed 2:3.28.4-0ubuntu0.16.04.3 |
| 14.04 LTS trusty | Fixed 2:3.28.4-0ubuntu0.14.04.3 |
| thunderbird | 18.10 cosmic | Fixed 1:52.4.0+build1-0ubuntu2 |
| 18.04 LTS bionic | Fixed 1:52.4.0+build1-0ubuntu2 |
| 17.10 artful | Fixed 1:52.4.0+build1-0ubuntu2 |
| 17.04 zesty | Fixed 1:52.4.0+build1-0ubuntu0.17.04.2 |
| 16.04 LTS xenial | Fixed 1:52.4.0+build1-0ubuntu0.16.04.2 |
| 14.04 LTS trusty | Fixed 1:52.4.0+build1-0ubuntu0.14.04.2 |

---

* [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-2017-7805?format=md#patch-details)

### 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 |
| --- | --- |
| nss | * Upstream:   <https://hg.mozilla.org/projects/nss/rev/839200ce0943166a079284bdf45dcc37bb672925> |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

7.5 · High

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 7.5 · High |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-7805)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2017-7805)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2017-7805)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2017-7805)

### Related Ubuntu Security Notices (USN)

+ [USN-3436-1](https://usn.ubuntu.com/USN-3436-1)
+ Thunderbird vulnerabilities
+ 11 October 2017

+ [USN-3431-1](https://usn.ubuntu.com/USN-3431-1)
+ NSS vulnerability
+ 2 October 2017

+ [USN-3435-1](https://usn.ubuntu.com/USN-3435-1)
+ Firefox vulnerabilities
+ 2 October 2017

### Other references

* <https://www.mozilla.org/en-US/security/advisories/mfsa2017-22/>
* <https://www.mozilla.org/en-US/security/advisories/mfsa2017-21/>
* <https://www.cve.org/CVERecord?id=CVE-2017-7805>