Anthropic Claude Code < 2.1.2 Sandbox Escape via settings.json Injection (CVE-2026-25725)

high Nessus Plugin ID 305986

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Synopsis

An application installed on the remote host is affected by a sandbox escape vulnerability.

Description

The version of Anthropic Claude Code installed on the remote host is prior to 2.1.2. It is, therefore, affected by a sandbox escape vulnerability.

The bubblewrap sandboxing mechanism failed to properly protect the .claude/settings.json configuration file when it did not exist at startup. While the parent directory was mounted as writable and .claude/settings.local.json was explicitly protected with read-only constraints, settings.json was not protected if it was missing. This allowed malicious code running inside the sandbox to create this file and inject persistent hooks such as SessionStart commands that would execute with host privileges when Claude Code was restarted.
(CVE-2026-25725)

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

Solution

Upgrade Anthropic Claude Code to version 2.1.2 or later.

Plugin Details

Severity: High

ID: 305986

File Name: anthropic_claude_code_CVE-2026-25725.nasl

Version: 1.2

Type: Local

Agent: unix

Family: Misc.

Published: 4/10/2026

Updated: 4/13/2026

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.3

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.4

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

CVSS Score Source: CVE-2026-25725

CVSS v3

Risk Factor: Critical

Base Score: 10

Temporal Score: 8.7

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

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

CVSS v4

Risk Factor: High

Base Score: 7.7

Threat Score: 5.2

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Vulnerability Information

CPE: cpe:/a:anthropic:claude_code

Required KB Items: installed_sw/Anthropic Claude Code

Exploit Ease: No known exploits are available

Patch Publication Date: 2/6/2026

Vulnerability Publication Date: 2/6/2026

Reference Information

CVE: CVE-2026-25725

IAVA: 2026-A-0304

Detections

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