Bug 2562165 (CVE-2026-57194)

Summary: CVE-2026-57194 asterisk: Asterisk: Denial of Service via out-of-bounds write in chan_unistim
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Asterisk. An out-of-bounds write vulnerability in the chan_unistim channel driver allows a remote attacker to cause a Denial of Service (DoS) by crashing the Asterisk service. By sending a specially crafted network request to an exposed chan_unistim port, an attacker can overflow an internal memory buffer during dial digit processing. This flaw requires the chan_unistim module to be loaded and accessible, allowing an attacker to disrupt telephony operations.
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Bug Depends On: 2564818, 2564819, 2564821, 2564822    
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Description OSIDB Bzimport 2026-10-27 18:09:24 UTC 
Asterisk is an open source private branch exchange and telephony toolkit. Prior to Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3, an out-of-bounds write in `chan_unistim` `DIALPAGE` digit handling can overflow the `phone_number` field and crash Asterisk when an attacker sends a carefully crafted incoming request packet. The `chan_unistim` module must be loaded and configured with a valid `UNISTIM UDP port` that the attacker can reach. The attacker must register as a configured `phone MAC`, or the deployment must have an equivalent `production/autoprovisioning` path that allows the client to reach the main page. This issue is fixed in Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3.