CVE-2026-0637: Information Disclosure Vulnerability

CVE-2026-0637 Overview

CVE-2026-0637 is an information disclosure vulnerability affecting WSO2 products that use the Event Publisher output adapter. When the adapter is configured with irrelevant properties, the affected products log those property values to the wso2carbon log files without adequate validation or sanitization. An attacker with local access to these log files can retrieve sensitive information, including user credentials and other confidential data inadvertently written by misconfigured adapters. The issue is tracked under [CWE-532: Insertion of Sensitive Information into Log File]. WSO2 has published details in the WSO2 Security Advisory WSO2-2025-4897.

Critical Impact
Sensitive property values including credentials may be written in cleartext to wso2carbon log files, enabling privileged local users to harvest confidential data and pivot to unauthorized access.

Affected Products

WSO2 products implementing the Event Publisher output adapter (see the vendor advisory for the complete affected version list)
Deployments configured with output adapters containing irrelevant or misconfigured properties
Systems where the wso2carbon log files are accessible to users beyond the intended administrative scope

Discovery Timeline

2026-08-06 - CVE-2026-0637 published to NVD
2026-08-06 - Last updated in NVD database

Technical Details for CVE-2026-0637

Vulnerability Analysis

The defect resides in how the Event Publisher output adapter processes its configuration. When the adapter receives properties that are not relevant to its expected schema, it writes those property values into the wso2carbon log stream. The logging path does not validate or sanitize the values before serialization, so any secret placed into a misconfigured property is persisted verbatim.

The consequence is a classic sensitive information exposure through log files. Credentials, API tokens, and other secrets that operators supply during configuration can end up in log records that outlive the runtime session. Because logs are typically retained, forwarded to central aggregators, and read by lower-privileged operational roles, the blast radius extends beyond the original administrator boundary.

Exploitation requires an actor already holding high privileges on the local host to read the wso2carbon logs. The vulnerability does not itself grant code execution or write access, but it converts logged secrets into a reusable credential source for further lateral movement.

Root Cause

The root cause is missing output encoding and property filtering in the Event Publisher adapter's configuration handler. The component logs unrecognized properties for diagnostic purposes but treats every property value as non-sensitive. There is no allow-list of loggable fields and no redaction pass for values that resemble secrets, which is the pattern described in [CWE-532].

Attack Vector

The attack vector is local. An authenticated actor with access to the wso2carbon log files, either directly on disk or through a downstream log collector, opens the log and searches for the property names emitted by the misconfigured adapter. The adjacent value contains the sensitive data. The actor then reuses those credentials against the WSO2 deployment or connected systems to gain unauthorized access.

No verified public exploit code is available for CVE-2026-0637. Refer to the WSO2 Security Advisory WSO2-2025-4897 for vendor-provided technical detail.

Detection Methods for CVE-2026-0637

Indicators of Compromise

Entries in wso2carbon.log containing unexpected property names alongside values that resemble passwords, API keys, or bearer tokens.
Access patterns showing non-administrative accounts reading WSO2 log directories or pulling archived log bundles.
Downstream log aggregator queries filtering on Event Publisher adapter property names shortly after configuration changes.

Detection Strategies

Scan existing wso2carbon log files for high-entropy strings, credential-like patterns, and known secret formats to identify prior disclosure.
Correlate WSO2 configuration change events with subsequent log reads by non-administrative principals to surface potential abuse.
Alert on Event Publisher adapter deployments that include property keys outside the documented adapter schema.

Monitoring Recommendations

Forward wso2carbon logs to a centralized platform with redaction at ingest and tightly scoped access controls.
Monitor filesystem access to the WSO2 repository/logs/ directory and flag reads by unexpected users or service accounts.
Track configuration deployments of Event Publisher adapters and review them for irrelevant properties before promotion.

How to Mitigate CVE-2026-0637

Immediate Actions Required

Review all Event Publisher output adapter configurations and remove properties that are not part of the adapter's documented schema.
Rotate any credentials or secrets that may have been placed into adapter configuration properties prior to remediation.
Restrict read access to the wso2carbon log files and the WSO2 repository/logs/ directory to a minimal set of administrators.
Purge or redact historical log files that contain sensitive property values, including copies held by log aggregators and backups.

Patch Information

Consult the WSO2 Security Advisory WSO2-2025-4897 for the authoritative list of affected products, fixed versions, and patch instructions. Apply the WSO2-provided update or WUM update for each affected product in the environment.

Workarounds

Configure Event Publisher output adapters with only the properties defined by the adapter specification; reject any deployment that introduces unknown keys.
Raise the log level for the affected components so that misconfiguration diagnostics are suppressed until the patch is applied.
Apply operating system access controls and file permissions so that only the WSO2 runtime account and designated administrators can read wso2carbon.log.

bash

# Configuration example: restrict access to wso2carbon log files
sudo chown -R wso2carbon:wso2admins /opt/wso2/repository/logs
sudo chmod 750 /opt/wso2/repository/logs
sudo chmod 640 /opt/wso2/repository/logs/wso2carbon.log

# Search existing logs for potentially disclosed secrets before rotation
grep -Ei 'password|secret|token|apikey' /opt/wso2/repository/logs/wso2carbon.log*