Asterisk PBX up to 23.2.1 xml.c ast_xml_open xml external entity reference

CVSS Meta Temp Score
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CTI Interest Score
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4.1$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic has been found in Asterisk PBX up to 20.7-cert8/20.18.1/21.12.0/22.8.1/23.2.1. This impacts the function ast_xml_open of the file xml.c. This manipulation causes xml external entity reference. The identification of this vulnerability is CVE-2026-23739. It is possible to initiate the attack remotely. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Asterisk PBX up to 20.7-cert8/20.18.1/21.12.0/22.8.1/23.2.1 and classified as problematic. Affected by this vulnerability is the function ast_xml_open of the file xml.c. The manipulation with an unknown input leads to a xml external entity reference vulnerability. The CWE definition for the vulnerability is CWE-611. The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Asterisk is an open source private branch exchange and telephony toolkit. Prior to versions 20.7-cert9, 20.18.2, 21.12.1, 22.8.2, and 23.2.2, the ast_xml_open() function in xml.c parses XML documents using libxml with unsafe parsing options that enable entity expansion and XInclude processing. Specifically, it invokes xmlReadFile() with the XML_PARSE_NOENT flag and later processes XIncludes via xmlXIncludeProcess().If any untrusted or user-supplied XML file is passed to this function, it can allow an attacker to trigger XML External Entity (XXE) or XInclude-based local file disclosure, potentially exposing sensitive files from the host system. This can also be triggered in other cases in which the user is able to supply input in xml format that triggers the asterisk process to parse it. This issue has been patched in versions 20.7-cert9, 20.18.2, 21.12.1, 22.8.2, and 23.2.2.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-23739 since 01/15/2026. The exploitation appears to be difficult. The attack can be launched remotely. Additional levels of successful authentication are needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 298277 (Linux Distros Unpatched Vulnerability : CVE-2026-23739), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 20.7-cert9, 20.18.2, 21.12.1, 22.8.2 or 23.2.2 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (298277) and CERT Bund (WID-SEC-2026-0327). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • Open Source Asterisk

Productinfo

Type

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.1
VulDB Meta Temp Score: 4.1

VulDB Base Score: 3.9
VulDB Temp Score: 3.8
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 6.5
NVD Vector: 🔒

CNA Base Score: 2.0
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Xml external entity reference
CWE: CWE-611 / CWE-610
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 298277
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-23739

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: PBX 20.7-cert9/20.18.2/21.12.1/22.8.2/23.2.2

Timelineinfo

01/15/2026 CVE reserved
02/06/2026 +22 days Advisory disclosed
02/06/2026 +0 days VulDB entry created
02/19/2026 +12 days VulDB entry last update

Sourcesinfo

Advisory: GHSA-85x7-54wr-vh42
Status: Confirmed

CVE: CVE-2026-23739 (🔒)
GCVE (CVE): GCVE-0-2026-23739
GCVE (VulDB): GCVE-100-344749
CERT Bund: WID-SEC-2026-0327 - Asterisk: Mehrere Schwachstellen

Entryinfo

Created: 02/06/2026 21:37
Updated: 02/19/2026 00:37
Changes: 02/06/2026 21:37 (67), 02/07/2026 05:14 (7), 02/07/2026 11:50 (2), 02/19/2026 00:37 (11)
Complete: 🔍
Cache ID: 216::103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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