Vulnerability Details : CVE-2016-9938

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.
Published 2016-12-12 21:59:02
Updated 2017-07-27 01:29:07
Source MITRE
View at NVD,   CVE.org
Vulnerability category: BypassGain privilege

Products affected by CVE-2016-9938

Threat overview for CVE-2016-9938

Top countries where our scanners detected CVE-2016-9938
Top open port discovered on systems with this issue 8088
IPs affected by CVE-2016-9938 10,046
Threat actors abusing to this issue? Yes
Find out if you* are affected by CVE-2016-9938!
*Directly or indirectly through your vendors, service providers and 3rd parties. Powered by attack surface intelligence from SecurityScorecard.

Exploit prediction scoring system (EPSS) score for CVE-2016-9938

EPSS FAQ
1.67%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 87 %
Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2016-9938

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
5.0
 MEDIUM AV:N/AC:L/Au:N/C:N/I:P/A:N
10.0
2.9
 NIST
5.3
 MEDIUM CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
3.9
1.4
 NIST

CWE ids for CVE-2016-9938

  • The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action.
    Assigned by: nvd@nist.gov (Primary)

References for CVE-2016-9938

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