CVE-2026-12823: Browserbase Privilege Escalation Vulnerability

CVE-2026-12823 Overview

CVE-2026-12823 affects Browserbase versions up to 20260526. The flaw resides in the Autobrowse Trace Artifact Handler component and stems from incorrect default permissions assigned to trace artifacts written by the application. A local attacker with low privileges can read or interact with these artifacts because the default permissions do not enforce least-privilege access. Public proof-of-concept material has been released, increasing the likelihood of opportunistic local abuse. The vendor was contacted prior to disclosure but did not respond. The weakness is categorized under CWE-266: Incorrect Default Permissions.

Critical Impact
A local user can access Autobrowse trace artifacts that may contain sensitive browsing session data due to incorrect default file permissions.

Affected Products

Browserbase versions up to and including 20260526
Browserbase Skills Autobrowse Trace Artifact Handler component
Local deployments exposing trace artifacts to multi-user systems

Discovery Timeline

2026-06-22 - CVE CVE-2026-12823 published to NVD
2026-06-23 - Last updated in NVD database

Technical Details for CVE-2026-12823

Vulnerability Analysis

The vulnerability is an insecure file permissions issue in the Autobrowse Trace Artifact Handler of Browserbase. When the component writes trace artifacts to disk, it assigns permissive default permissions that allow other local users to read the resulting files. Trace artifacts in browser automation tooling typically include captured network traffic, screenshots, DOM snapshots, and timing data. Any local actor with shell access to the host can therefore retrieve session telemetry that should remain restricted to the owning process or user.

Exploitation requires only a local approach with low privileges and no user interaction. The impact is limited to confidentiality of artifacts on disk and does not directly affect integrity or availability of the Browserbase service.

Root Cause

The root cause is the failure to apply restrictive umask or explicit chmod semantics when creating trace artifact files. Files are written with world-readable or group-readable permissions instead of being scoped to the owning user. This maps to CWE-266: Incorrect Default Permissions, where the application relies on the operating system's default permission inheritance rather than enforcing a least-privilege policy at artifact creation.

Attack Vector

An attacker requires an authenticated local account on the host running Browserbase. After identifying the directory where Autobrowse stores trace artifacts, the attacker reads files directly using standard filesystem utilities. No exploit code or memory corruption primitive is required because the operating system honors the overly permissive mode bits set by the application. The published proof-of-concept demonstrates artifact enumeration and direct read access. See the GitHub Advisory for CVE-2026-12823 and the GitHub PoC Script for technical details.

Detection Methods for CVE-2026-12823

Indicators of Compromise

Trace artifact files in Browserbase output directories with mode bits permitting non-owner read access (for example 0644 or broader where 0600 is expected).
Access events from local user accounts that do not match the Browserbase service account reading files under the Autobrowse trace directory.
Unexpected copies of trace artifacts in user home directories or staging paths outside the Browserbase working directory.

Detection Strategies

Audit filesystem permissions on directories storing Autobrowse trace artifacts using find <path> -type f -not -perm 600.
Enable Linux auditd or equivalent kernel auditing on the trace artifact path to capture open() and read() calls from non-service UIDs.
Review process accounting logs for cross-user access to Browserbase artifact paths.

Monitoring Recommendations

Continuously monitor file mode changes on Autobrowse trace directories and alert on creation of artifacts with permissions broader than the service account.
Track user-to-file access ratios on the host and flag accounts that read artifacts outside their ownership scope.
Forward host telemetry into a centralized analytics pipeline for correlation with authentication and shell session activity.

How to Mitigate CVE-2026-12823

Immediate Actions Required

Restrict permissions on existing Autobrowse trace artifact directories to 0700 and artifact files to 0600 owned by the Browserbase service account.
Limit interactive local access on hosts running Browserbase to administrators only until a vendor fix is available.
Move trace artifact storage to a dedicated filesystem path that is not shared with other local users or services.

Patch Information

No vendor patch has been published. The vendor did not respond to the disclosure attempt. Track the VulDB entry for CVE-2026-12823 and the VulDB Vulnerability Detail #372613 for updates on a fixed release.

Workarounds

Set a restrictive umask 077 for the user or service account that runs Browserbase so newly created artifacts inherit owner-only permissions.
Apply post-creation hardening with a wrapper or systemd ExecStartPost step that runs chmod 600 on artifacts under the trace output directory.
Encrypt the filesystem or directory where trace artifacts are written so that local read access does not yield plaintext data.

bash

# Configuration example: enforce least-privilege on Autobrowse trace artifacts
umask 077
chown -R browserbase:browserbase /var/lib/browserbase/autobrowse/traces
chmod 700 /var/lib/browserbase/autobrowse/traces
find /var/lib/browserbase/autobrowse/traces -type f -exec chmod 600 {} \;