Vulnerability Note VU#155412

Samsung Galaxy S phones fail to properly validate SwiftKey language pack updates

Original Release date: 16 Jun 2015 | Last revised: 25 Jun 2015


Samsung Galaxy S phones, including the S4 Mini, S4, S5, and S6, fail to properly validate Swiftkey language pack updates.


CWE-345: Insufficient Verification of Data Authenticity - CVE-2015-4640

Samsung Galaxy S phones, including the S4 Mini, S4, S5, and S6, are pre-installed with a version of SwiftKey keyboard that is signed by Samsung to operate with system privileges. By design, SwiftKey periodically checks for language pack updates over HTTP (CVE-2015-4640). By intercepting such requests and modifying the necessary fields, an attacker can write arbitrary data to vulnerable devices.

SwiftKey has stated that the "vulnerability is unrelated to and does not affect our SwiftKey consumer apps on Google Play and the Apple App Store."


A remote, unauthenticated attacker conducting a man-in-the-middle attack may be able to write arbitrary data to vulnerable devices checking for updates. Based on the frequency of SwiftKey update checks, which "appears to be every 8 hours" according to NowSecure researchers, such an attack may have a low likelihood of occurring.


Apply an update

Samsung has provided a firmware update to cell phone carriers for distribution to affected users. If your cell phone carrier has not provided the over-the-air update, consider the following workaround:

Avoid untrusted networks

Avoid using untrusted networks, including public WiFi. Using your device on an untrusted network increases the chance of falling victim to a MITM attack.

Vendor Information (Learn More)

VendorStatusDate NotifiedDate Updated
SamsungAffected02 Mar 201516 Jun 2015
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

Group Score Vector
Base 5.7 AV:A/AC:M/Au:N/C:N/I:C/A:N
Temporal 4.5 E:POC/RL:OF/RC:C
Environmental 4.5 CDP:N/TD:H/CR:ND/IR:ND/AR:ND



Thanks to Ryan Welton and Ted Eull of NowSecure for reporting this vulnerability.

This document was written by Joel Land.

Other Information

  • CVE IDs: CVE-2015-4640 CVE-2015-4641
  • Date Public: 16 Jun 2015
  • Date First Published: 16 Jun 2015
  • Date Last Updated: 25 Jun 2015
  • Document Revision: 32


If you have feedback, comments, or additional information about this vulnerability, please send us email.