Atlassian Confluence 7.1.x < 9.2.26 / 9.3.x < 10.2.17 / 11.0.0 (CONFSERVER-104421)

high Nessus Plugin ID 368971

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Synopsis

The remote Atlassian Confluence host is missing a security update.

Description

The version of Atlassian Confluence Server running on the remote host is affected by a vulnerability as referenced in the CONFSERVER-104421 advisory.

- jackson-databind contains the general-purpose data-binding functionality and tree-model for Jackson Data Processor. From 2.10.0 until 2.18.8, 2.21.4, and 3.1.4, jackson-databind's PolymorphicTypeValidator (PTV) is the primary safety mechanism guarding polymorphic deserialization. When polymorphic typing is enabled and a type identifier contains generic parameters (i.e. the type ID string contains <), DatabindContext._resolveAndValidateGeneric() validates only the raw container class name (the substring before <) against the configured PTV. If the container type is approved, the method parses the full canonical type string via TypeFactory.constructFromCanonical() and returns the fully parameterized type without ever validating the nested type arguments against the PTV. The nested type arguments are then resolved, instantiated, and populated as beans during deserialization. An attacker who controls the type ID can therefore place a denied class as a generic type parameter of an allowed container for example java.util.ArrayList<com.evil.Gadget> when only java.util.ArrayList is allow-listed. The container passes the PTV check; com.evil.Gadget is loaded via Class.forName(name, true, loader), instantiated, and its properties are set from attacker-controlled JSON. This completely bypasses an explicitly configured PTV allow-list. This vulnerability is fixed in 2.18.8, 2.21.4, and 3.1.4. (CVE-2026-54512)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Upgrade to Atlassian Confluence version 9.2.26, 10.2.17, 11.0.0 or later.

Plugin Details

Severity: High

ID: 368971

File Name: confluence_confserver-104421.nasl

Version: 1.2

Type: Combined

Agent: windows, macosx, unix

Family: CGI abuses

Published: 10/21/2026

Updated: 10/22/2026

Configuration: Enable thorough checks (optional)

Supported Sensors: Nessus Agent, Nessus

Enable CGI Scanning: true

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 58.09

CVSS v2

Risk Factor: High

Base Score: 7.6

Temporal Score: 6

Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2026-54512

CVSS v3

Risk Factor: High

Base Score: 8.1

Temporal Score: 7.3

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:atlassian:confluence

Required KB Items: installed_sw/Atlassian Confluence

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 9/2/2026

Vulnerability Publication Date: 6/23/2026

Reference Information

CVE: CVE-2026-54512

Detections

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