CVE-2026-50639: Perl Metrics::Any Injection Vulnerability

CVE-2026-50639 Overview

CVE-2026-50639 is a metric injection vulnerability in the Perl module Metrics::Any::Adapter::SignalFx versions before 0.04. The module fails to sanitize user-controlled input before transmitting StatsD-formatted metric packets. The StatsD protocol and its dogstatsd extension support multiple newline-separated metrics per packet, allowing attackers to inject arbitrary metrics through unfiltered input. The _labels function additionally does not validate tag labels for newlines or StatsD control characters, enabling label-based injection. This issue is classified under [CWE-93] Improper Neutralization of CRLF Sequences. The flaw affects observability pipelines where application data feeds into SignalFx metric streams.

Critical Impact
Attackers can inject forged metrics into telemetry pipelines, corrupting monitoring data, masking incidents, or triggering false alerts in downstream observability platforms.

Affected Products

Metrics::Any::Adapter::SignalFx for Perl, versions before 0.04
Applications using Metrics::Any::Adapter::Statsd as a transitive dependency (see CVE-2026-50637)
Observability stacks ingesting StatsD or dogstatsd traffic from affected Perl services

Discovery Timeline

2026-06-10 - CVE-2026-50639 published to NVD
2026-06-10 - Last updated in NVD database

Technical Details for CVE-2026-50639

Vulnerability Analysis

The Metrics::Any::Adapter::SignalFx module extends Metrics::Any::Adapter::Statsd to ship application metrics to SignalFx-compatible collectors over the StatsD wire format. The StatsD protocol treats the newline character (\n) as a metric separator within a single UDP or TCP payload. When an application forwards untrusted input — such as user identifiers, request paths, or tag values — into a metric name or label without escaping, an attacker can embed \n followed by a fully formed StatsD line.

The receiving collector parses the injected line as a legitimate metric. This allows attackers to write arbitrary counters, gauges, or timers into the telemetry backend. The _labels helper compounds the issue by emitting tag strings without filtering newlines or StatsD control characters such as |, :, and #. Label injection lets attackers manipulate dimensional metadata that drives alert routing and dashboard aggregation.

Root Cause

The root cause is missing input neutralization in the metric serialization path. Neither the metric name handler nor the _labels function rejects or escapes characters with protocol-level meaning. Version 0.04 introduces sanitization of control characters in both code paths, mirroring the fix in the upstream Metrics::Any::Adapter::Statsd module.

Attack Vector

An attacker supplies crafted input — through HTTP headers, request bodies, query parameters, or any other field an application records as a metric label or name. When the Perl service emits the metric, the embedded newline terminates the legitimate line and the attacker-controlled bytes are interpreted as a new metric. The attack reaches the metrics collector over the network and requires no authentication on the vulnerable service path.

Refer to the MetaCPAN release changes for the technical fix details. No verified public proof-of-concept code is available.

Detection Methods for CVE-2026-50639

Indicators of Compromise

Unexpected metric names or namespaces appearing in SignalFx or StatsD-compatible backends that do not match the application's instrumentation code.
Spikes in metric cardinality driven by tag values containing user-supplied strings.
Metric submissions with anomalous timestamps, counter values, or tag combinations not produced by the application's normal code paths.

Detection Strategies

Inventory Perl services and identify those depending on Metrics::Any::Adapter::SignalFx at versions below 0.04 using CPAN manifests or cpanfile.snapshot.
Inspect application code for paths that pass request-derived strings to metric name or label arguments without prior sanitization.
Audit StatsD ingestion logs for payloads containing embedded \n, |, :, or # characters in unexpected positions.

Monitoring Recommendations

Forward StatsD collector logs into a SIEM and alert on metric names that do not match an allowlist derived from source code.
Track week-over-week tag cardinality per metric and alert on sudden expansion that may indicate injected labels.
Monitor downstream alerting rules for suppression or override patterns triggered by attacker-controlled metric values.

How to Mitigate CVE-2026-50639

Immediate Actions Required

Upgrade Metrics::Any::Adapter::SignalFx to version 0.04 or later across all Perl deployments.
Upgrade the transitive dependency Metrics::Any::Adapter::Statsd to the patched release referenced in CVE-2026-50637.
Audit application code paths that incorporate untrusted input into metric names, values, or labels and add explicit sanitization.

Patch Information

The upstream fix ships in Metrics-Any-Adapter-Statsd-0.04 on CPAN. Review the MetaCPAN release changes for the exact sanitization changes. The related CVE records CVE-2026-50637 and CVE-2026-9270 document the parallel issues in the underlying StatsD adapter.

Workarounds

Wrap metric emission calls with a sanitizer that strips \n, \r, |, :, and # from any user-derived strings before they reach the adapter.
Restrict tag values to an allowlist of expected characters such as [A-Za-z0-9_.-] and reject or truncate the remainder.
Place the StatsD collector behind a parser that validates each line against a strict metric schema and drops malformed submissions.

bash

# Configuration example: pin the patched version in cpanfile
requires 'Metrics::Any::Adapter::SignalFx', '>= 0.04';
requires 'Metrics::Any::Adapter::Statsd',   '>= 0.04';

# Rebuild dependencies and verify the installed version
cpanm --installdeps .
perl -MMetrics::Any::Adapter::SignalFx \
     -E 'say $Metrics::Any::Adapter::SignalFx::VERSION'