Vulnerability Monitor

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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.


Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 5.3, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts limited integrity, for affected systems. Impacting 2 products from digium, from digium organizations running these solutions should prioritize assessment and patching.

Historical Context

First disclosed in 2016, this vulnerability was reported during a period defined by widespread IoT adoption challenges, mobile security concerns, and the emergence of advanced persistent threat (APT) techniques. Contemporary mitigation strategies focused on secure development practices and third-party component vetting.


Published

2016-12-12T21:59:01.617

Last Modified

2026-05-06T22:30:45.220

Status

Modified

Source

[email protected]

Severity

CVSSv3.0: 5.3 (MEDIUM)

CVSSv2 Vector

AV:N/AC:L/Au:N/C:N/I:P/A:N

  • Access Vector: NETWORK
  • Access Complexity: LOW
  • Authentication: NONE
  • Confidentiality Impact: NONE
  • Integrity Impact: PARTIAL
  • Availability Impact: NONE
Exploitability Score

10.0

Impact Score

2.9

Weaknesses
  • Type: Primary
    CWE-285

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Application digium asterisk 11.0.0 Yes
Application digium asterisk 11.0.0 Yes
Application digium asterisk 11.0.0 Yes
Application digium asterisk 11.0.0 Yes
Application digium asterisk 11.0.0 Yes
Application digium asterisk 11.0.1 Yes
Application digium asterisk 11.0.2 Yes
Application digium asterisk 11.1.0 Yes
Application digium asterisk 11.1.0 Yes
Application digium asterisk 11.1.0 Yes
Application digium asterisk 11.1.1 Yes
Application digium asterisk 11.1.2 Yes
Application digium asterisk 11.2.0 Yes
Application digium asterisk 11.2.0 Yes
Application digium asterisk 11.2.0 Yes
Application digium asterisk 11.2.1 Yes
Application digium asterisk 11.2.2 Yes
Application digium asterisk 11.3.0 Yes
Application digium asterisk 11.4.0 Yes
Application digium asterisk 11.5.0 Yes
Application digium asterisk 11.5.1 Yes
Application digium asterisk 11.6.0 Yes
Application digium asterisk 11.6.1 Yes
Application digium asterisk 11.7.0 Yes
Application digium asterisk 11.8.0 Yes
Application digium asterisk 11.8.1 Yes
Application digium asterisk 11.9.0 Yes
Application digium asterisk 11.10.0 Yes
Application digium asterisk 11.10.1 Yes
Application digium asterisk 11.10.2 Yes
Application digium asterisk 11.11.0 Yes
Application digium asterisk 11.12.0 Yes
Application digium asterisk 11.12.1 Yes
Application digium asterisk 11.13.0 Yes
Application digium asterisk 11.13.1 Yes
Application digium asterisk 11.14.0 Yes
Application digium asterisk 11.14.1 Yes
Application digium asterisk 11.14.2 Yes
Application digium asterisk 11.15.0 Yes
Application digium asterisk 11.15.1 Yes
Application digium asterisk 11.16.0 Yes
Application digium asterisk 11.17.0 Yes
Application digium asterisk 11.17.1 Yes
Application digium asterisk 11.18.0 Yes
Application digium asterisk 11.19.0 Yes
Application digium asterisk 11.20.0 Yes
Application digium asterisk 11.21.0 Yes
Application digium asterisk 11.21.1 Yes
Application digium asterisk 11.21.2 Yes
Application digium asterisk 11.22.0 Yes
Application digium asterisk 11.22.0 Yes
Application digium asterisk 11.23.0 Yes
Application digium asterisk 11.23.0 Yes
Application digium asterisk 11.23.1 Yes
Application digium asterisk 11.24.0 Yes
Application digium asterisk 11.24.1 Yes
Application digium asterisk 11.25.0 Yes
Application digium asterisk 13.0.0 Yes
Application digium asterisk 13.0.0 Yes
Application digium asterisk 13.0.0 Yes
Application digium asterisk 13.0.0 Yes
Application digium asterisk 13.0.1 Yes
Application digium asterisk 13.0.2 Yes
Application digium asterisk 13.1.0 Yes
Application digium asterisk 13.1.1 Yes
Application digium asterisk 13.2.0 Yes
Application digium asterisk 13.2.1 Yes
Application digium asterisk 13.3.0 Yes
Application digium asterisk 13.3.1 Yes
Application digium asterisk 13.3.2 Yes
Application digium asterisk 13.4.0 Yes
Application digium asterisk 13.5.0 Yes
Application digium asterisk 13.6.0 Yes
Application digium asterisk 13.7.0 Yes
Application digium asterisk 13.7.1 Yes
Application digium asterisk 13.7.2 Yes
Application digium asterisk 13.8.0 Yes
Application digium asterisk 13.8.0 Yes
Application digium asterisk 13.8.1 Yes
Application digium asterisk 13.8.2 Yes
Application digium asterisk 13.9.0 Yes
Application digium asterisk 13.9.1 Yes
Application digium asterisk 13.10.0 Yes
Application digium asterisk 13.10.0 Yes
Application digium asterisk 13.11.0 Yes
Application digium asterisk 13.11.1 Yes
Application digium asterisk 13.11.2 Yes
Application digium asterisk 13.12.0 Yes
Application digium asterisk 13.12.1 Yes
Application digium asterisk 13.12.2 Yes
Application digium asterisk 13.13.0 Yes
Application digium asterisk 14.0.0 Yes
Application digium asterisk 14.0.0 Yes
Application digium asterisk 14.0.0 Yes
Application digium asterisk 14.0.0 Yes
Application digium asterisk 14.0.0 Yes
Application digium asterisk 14.0.1 Yes
Application digium asterisk 14.0.2 Yes
Application digium asterisk 14.1.0 Yes
Application digium asterisk 14.1.1 Yes
Application digium asterisk 14.1.2 Yes
Application digium asterisk 14.2.0 Yes
Application digium certified_asterisk 11.0.0 Yes
Application digium certified_asterisk 11.0.0 Yes
Application digium certified_asterisk 11.0.0 Yes
Application digium certified_asterisk 11.1.0 Yes
Application digium certified_asterisk 11.1.0 Yes
Application digium certified_asterisk 11.1.0 Yes
Application digium certified_asterisk 11.1.0 Yes
Application digium certified_asterisk 11.2.0 Yes
Application digium certified_asterisk 11.2.0 Yes
Application digium certified_asterisk 11.2.0 Yes
Application digium certified_asterisk 11.3.0 Yes
Application digium certified_asterisk 11.3.0 Yes
Application digium certified_asterisk 11.3.0 Yes
Application digium certified_asterisk 11.4.0 Yes
Application digium certified_asterisk 11.4.0 Yes
Application digium certified_asterisk 11.4.0 Yes
Application digium certified_asterisk 11.4.0 Yes
Application digium certified_asterisk 11.5.0 Yes
Application digium certified_asterisk 11.5.0 Yes
Application digium certified_asterisk 11.5.0 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6 Yes
Application digium certified_asterisk 11.6.0 Yes
Application digium certified_asterisk 11.6.0 Yes
Application digium certified_asterisk 11.6.0 Yes
Application digium certified_asterisk 11.6.0 Yes

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For digium's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.