CVE-2026-57196
Received Received - Intake

Reflected XSS in Asterisk Phone Provisioning

Publication date: 2026-10-26

Last updated on: 2026-10-26

Assigner: GitHub, Inc.

Description
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 unauthenticated attacker may use reflected cross-site scripting in `phone provisioning HTTP error pages` to retrieve an authorized user's `AMI session cookie` and impersonate that user when `res_phoneprov` is enabled. The Asterisk HTTP web server, Asterisk Manager Interface (AMI), and AMI access via HTTP must all be enabled; each is disabled by default. The attacker must be able to connect to the HTTP server, which binds only to `127.0.0.1` by default even when enabled, and must convince the authorized user to click a malicious link. 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.

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Meta Information

Published
2026-10-26
Last Modified
2026-10-26
Generated
2026-10-26
AI Q&A
2026-10-26
EPSS Evaluated
N/A
NVD
CVE-2026-57196
EUVD
EUVD-2026-110074

Affected Vendors & Products

Showing 6 associated CPEs
Vendor Product Version / Range
asterisk asterisk < 20.20.1
asterisk asterisk >= 21.0.0-pre1, < 21.12.3
asterisk asterisk >= 22.0.0-pre1, < 22.10.1
asterisk asterisk >= 23.0.0-pre1, < 23.4.1
asterisk certified-asterisk < 20.7-cert11
asterisk certified-asterisk >= 22.8-cert1-pre1, < 22.8-cert3

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

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Executive Summary

This is a reflected Cross-Site Scripting (XSS) vulnerability in Asterisk's phone provisioning HTTP error pages. It occurs when the text parameter in error responses is inserted into HTML without proper escaping, allowing malicious HTML metacharacters in URIs to be rendered by browsers. Attackers can exploit this to inject scripts that steal an authorized user's AMI session cookie if they trick the user into clicking a malicious link.

Detection Guidance

Check if Asterisk is running vulnerable versions (<=20.20.0, <=21.12.2, <=22.10.0, <=23.4.0, or Certified Asterisk <=20.7-cert10, <=22.8-cert2) using commands like 'asterisk -V' or checking package versions. Verify if res_phoneprov module is enabled with 'module show like res_phoneprov' in Asterisk CLI. Inspect HTTP server logs for suspicious URI patterns or error responses containing unescaped HTML metacharacters.

Impact Analysis

An attacker could impersonate an authorized user by stealing their AMI session cookie, potentially gaining access to sensitive telephony functions. This requires the attacker to trick a user into clicking a malicious link while specific Asterisk components are enabled.

Mitigation Strategies
  • Upgrade Asterisk to patched versions (20.20.1, 21.12.3, 22.10.1, 23.4.1, or Certified Asterisk 20.7-cert11, 22.8-cert3) immediately.
  • Disable the res_phoneprov module if not required using 'module unload res_phoneprov' in Asterisk CLI.
  • Disable the Asterisk HTTP web server and AMI HTTP access if not needed by setting appropriate configuration options to false.
  • Restrict HTTP server binding to localhost (127.0.0.1) if external access is not required.

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