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CVE-2025-57767: Asterisk Vulnerability Affecting SIP Request Authentication

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Overview

The CVE-2025-57767 is a critical vulnerability in the Asterisk open-source PBX and telephony toolkit. Specifically affecting the SIP request authentication process, this bug could potentially lead to system compromise or data leakage if exploited. Given the widespread use of the Asterisk system, this vulnerability puts numerous businesses and individuals at risk worldwide.

Vulnerability Summary

CVE ID: CVE-2025-57767
Severity: High (7.5 CVSS)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System compromise and potential data leakage

Affected Products

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Product | Affected Versions

Asterisk PBX | <20.15.2 Asterisk PBX | <21.10.2 Asterisk PBX | <22.5.2 How the Exploit Works

The vulnerability lies within the get_authorization_header() function in res_pjsip_authenticator_digest. When a SIP request with an Authorization header containing a realm not previously included in a 401 response’s WWW-Authenticate header is received, or if an incorrect realm is received without a previous 401 response sent, the function returns a NULL. This return value is not appropriately checked before attempting to retrieve the digest algorithm, causing a SEGV, or segmentation fault. This could then be exploited by an attacker to compromise the system or leak data.

Conceptual Example Code

The malicious attacker might exploit the vulnerability by sending a SIP request with a manipulated Authorization header. This could look something like this:

INVITE sip:target@example.com SIP/2.0
Via: SIP/2.0/UDP attacker.com;branch=z9hG4bK74bf9
From: "Attacker" <sip:attacker@attacker.com>;tag=9fxced76sl
To: <sip:target@example.com>
Call-ID: 3848276298220188511@attacker.com
CSeq: 2 INVITE
Authorization: Digest username="user",realm="manipulated_realm",nonce="abc123",uri="sip:target@example.com",response="...",algorithm=MD5
Content-Length: 0

In this request, the ‘realm’ parameter in the Authorization header would be manipulated to an incorrect value, triggering the vulnerability.

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Disclaimer:

The information and code presented in this article are provided for educational and defensive cybersecurity purposes only. Any conceptual or pseudocode examples are simplified representations intended to raise awareness and promote secure development and system configuration practices.

Do not use this information to attempt unauthorized access or exploit vulnerabilities on systems that you do not own or have explicit permission to test.

Ameeba and its authors do not endorse or condone malicious behavior and are not responsible for misuse of the content. Always follow ethical hacking guidelines, responsible disclosure practices, and local laws.

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