CVE-2026-8722: Net::Async::Statsd::Client Metric Injection – Perl Monitoring Vulnerability

Technical summary

Net::Async::Statsd::Client through version 0.005 does not validate metric names against the statsd protocol specification. The statsd protocol uses newlines, colons, and pipes as delimiters and field separators. By crafting metric names containing these characters, an attacker can break out of the intended metric structure and inject additional metrics into the stream. This is classified as an improper input validation issue (CWE-150) combined with improper neutralization of special elements (CWE-93). With network-level access and no authentication required, an attacker can inject metrics if application code passes untrusted input directly to the client's metric methods.

Business impact

This vulnerability could allow an attacker to pollute monitoring and alerting systems with false metrics. In environments where observability data informs operational decisions, incident response, or compliance reporting, injected metrics could mask real performance issues, trigger false alerts, or corrupt historical metric data used for capacity planning and forensic analysis. Organizations relying on statsd metrics for security monitoring or SLA tracking may experience degraded visibility into actual application health.

Affected systems

Perl applications using Net::Async::Statsd::Client library version 0.005 and earlier are affected. This includes any production system that integrates this library to send application metrics to statsd monitoring backends (such as Graphite, InfluxDB, or other statsd-compatible aggregators). The vulnerability is present if untrusted user input or data from external sources is passed as metric names to the client.

Exploitability

Exploitation requires network access to the application and the ability to influence metric names sent to statsd. The attack vector is network-based with low complexity and no privilege or user interaction required (CVSS 3.1 score: 6.5, MEDIUM severity). If the application logs user-controlled data as metric names or derives metric names from request parameters, exploitation is straightforward. However, if metric names are hardcoded, the risk is reduced. The vulnerability has not been added to CISA's Known Exploited Vulnerabilities catalog.

Remediation

Upgrade Net::Async::Statsd::Client to a patched version released after 0.005. Verify the vendor's advisory for the specific version number. Until patching is possible, sanitize all metric names by removing or encoding newlines, colons, and pipes before passing them to the client library. Use a whitelist approach: only permit alphanumeric characters, underscores, and dots in metric names.

Patch guidance

Check the team net (Perl CPAN) repository for Net::Async::Statsd::Client updates newer than version 0.005. Apply the patch during your next maintenance window. Given the MEDIUM severity score and the requirement for an attacker to influence metric input, patching is important but not critical for systems with limited metric customization. Test patches in a staging environment to ensure no compatibility issues with your monitoring pipeline.

Detection guidance

Monitor for unusual patterns in statsd traffic: look for metric names containing newline characters (\n), multiple colons, or pipe characters (|) in unexpected positions. Check application logs for errors related to metric transmission or rejected metrics. Review statsd backend logs for suspicious metric entries that deviate from expected naming conventions. If using a Web Application Firewall, create rules to reject or log metric submissions containing protocol delimiter characters in suspicious combinations.

Why prioritize this

Assign this vulnerability MEDIUM priority. While the CVSS score is 6.5, the real-world impact depends heavily on whether your application accepts untrusted input for metric names and how critical your monitoring infrastructure is to operational security. Prioritize patching if you use statsd metrics for security alerting or if your application derives metric names from user input, query parameters, or external APIs. Deprioritize if metric names are hardcoded or tightly controlled internally.

Risk score, explained

The CVSS 3.1 score of 6.5 (MEDIUM) reflects the network attack vector, low complexity, and lack of privilege/interaction requirements, but is tempered by the limited scope of impact: the vulnerability affects data integrity and confidentiality of monitoring data, not system availability. The score does not account for context-dependent factors such as whether your organization's metrics are actually used for critical decision-making or compliance.

Frequently asked questions