--- title: "CVE-2016-9938\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-2016-9938?format=md keywords: index, follow --- # CVE-2016-9938 Publication date 12 December 2016 Last updated 26 August 2025 --- Ubuntu priority **Low** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) ## Cvss 3 Severity Score **5.3 · Medium** [Score breakdown](https://ubuntu.com/security/CVE-2016-9938?format=md#impact-score) Toggle side navigation ## Description An issue was discovered in Asterisk Open Source 11.x before 11.25.1, 13.x before 13.13.1, and 14.x before 14.2.1 and Certified Asterisk 11.x before 11.6-cert16 and 13.x before 13.8-cert4. The chan\_sip channel driver has a liberal definition for whitespace when attempting to strip the content between a SIP header name and a colon character. Rather than following RFC 3261 and stripping only spaces and horizontal tabs, Asterisk treats any non-printable ASCII character as if it were whitespace. This means that headers such as Contact\x01: will be seen as a valid Contact header. This mostly does not pose a problem until Asterisk is placed in tandem with an authenticating SIP proxy. In such a case, a crafty combination of valid and invalid To headers can cause a proxy to allow an INVITE request into Asterisk without authentication since it believes the request is an in-dialog request. However, because of the bug described above, the request will look like an out-of-dialog request to Asterisk. Asterisk will then process the request as a new call. The result is that Asterisk can process calls from unvetted sources without any authentication. If you do not use a proxy for authentication, then this issue does not affect you. If your proxy is dialog-aware (meaning that the proxy keeps track of what dialogs are currently valid), then this issue does not affect you. If you use chan\_pjsip instead of chan\_sip, then this issue does not affect you. ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | asterisk | 26.04 LTS resolute | Not affected | | 25.10 questing | Not affected | | 25.04 plucky | Not affected | | 24.10 oracular | Not affected | | 24.04 LTS noble | Not affected | | 23.10 mantic | Not affected | | 23.04 lunar | Not affected | | 22.10 kinetic | Not affected | | 22.04 LTS jammy | Not affected | | 21.10 impish | Not affected | | 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 | Ignored end of life | | 17.04 zesty | Ignored end of life | | 16.10 yakkety | Ignored end of life | | 16.04 LTS xenial | Vulnerable | | 14.04 LTS trusty | Not in release | | 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) ## Severity score breakdown CVSS version: CVSS v3.0 **Base score** 5.3 · Medium * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Network | | Attack complexity | Low | | Privileges required | None | | User interaction | None | | Scope | Unchanged | | Confidentiality impact | None | | Integrity impact | Low | | Availability impact | None | * Scores | Parameter | Value | | --- | --- | | Base score | 5.3 · Medium | | Exploitability score | - | | Impact score | - | **Vector:** CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-9938) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2016-9938) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2016-9938) * [Debian](https://security-tracker.debian.org/tracker/CVE-2016-9938) ### Other references * * *