CVE-2026-50637: Metrics::Any::Adapter::Statsd Injection

CVE-2026-50637 Overview

CVE-2026-50637 affects the Perl module Metrics::Any::Adapter::Statsd in versions prior to 0.04. The module fails to validate metric names and values before transmitting them over the statsd protocol. Because the statsd protocol uses newlines to delimit multiple metrics in a single packet, attacker-controlled input containing newline characters, colons, or pipes can inject arbitrary metrics into the telemetry stream. The flaw is categorized as [CWE-93] Improper Neutralization of CRLF Sequences. Version 0.04 resolves the issue by rejecting metric names that contain characters below ASCII 32, colons, or pipes.

Critical Impact
Attackers controlling metric inputs can forge, alter, or pollute statsd telemetry, corrupting monitoring data and potentially masking malicious activity.

Affected Products

Metrics::Any::Adapter::Statsd for Perl, versions prior to 0.04
Applications consuming the module with untrusted input mapped to metric names or values
Statsd-based observability pipelines receiving data from affected adapters

Discovery Timeline

2026-06-10 - CVE-2026-50637 published to NVD
2026-06-10 - Last updated in NVD database

Technical Details for CVE-2026-50637

Vulnerability Analysis

The statsd protocol and its extensions allow multiple metrics to be transmitted in a single UDP or TCP packet, separated by newline characters. Each metric uses a structured format where colons separate the metric name from its value, and pipes separate the value from the metric type indicator. The Metrics::Any::Adapter::Statsd adapter exposes a send method that serializes metric names and values into this wire format. In versions prior to 0.04, the _make helper that builds the on-wire payload performs no validation on the metric name or value strings. Any caller that passes user-influenced data into a metric name or value can therefore embed control characters that the receiving statsd daemon will interpret as additional metrics. This is a classic injection pattern (CRLF-style) translated into the statsd telemetry protocol.

Root Cause

The root cause is missing input neutralization in the _make method. The function concatenates metric components into the statsd wire format without rejecting or escaping newline, colon, or pipe characters that carry syntactic meaning in the protocol. The fix in 0.04 adds a guard that blocks metric names containing characters below ASCII 32 or the protocol delimiters : and |.

Attack Vector

Exploitation requires that an upstream caller passes attacker-controlled data into either the metric name or metric value argument. The attacker supplies a payload that includes a newline followed by a fabricated metric line. When the adapter serializes and sends the buffer, the statsd server parses the smuggled line as a legitimate metric. Consequences include falsifying counters and gauges, injecting metrics that trigger or suppress monitoring alerts, and polluting downstream dashboards and time-series databases. The vulnerability does not yield remote code execution against the statsd daemon, but it undermines the integrity of observability data that security and operations teams rely on.

No verified proof-of-concept code is published in the referenced advisory. See the MetaCPAN Change Log for the corrective commit and behavioral changes introduced in 0.04.

Detection Methods for CVE-2026-50637

Indicators of Compromise

Unexpected metric names appearing in statsd backends that do not correspond to any instrumented call site in application code
Sudden spikes or drops in counter and gauge values that lack a corresponding application event or deploy
Statsd packets containing embedded newline sequences in fields originating from user-supplied input

Detection Strategies

Inventory Perl applications and CPAN dependencies to identify deployments of Metrics::Any::Adapter::Statsd below version 0.04
Inspect call sites that pass HTTP parameters, request paths, usernames, or other untrusted strings into metric name or value arguments
Capture statsd traffic at the network edge and flag payloads containing \n, :, or | characters inside fields that should be alphanumeric

Monitoring Recommendations

Alert on the appearance of new, previously unseen metric keys in the statsd backend, especially keys that resemble user input
Correlate anomalous metric values with application logs to detect forged telemetry intended to mask malicious activity
Log and review module versions during CI/CD builds to prevent regression to pre-0.04 releases

How to Mitigate CVE-2026-50637

Immediate Actions Required

Upgrade Metrics::Any::Adapter::Statsd to version 0.04 or later across all Perl deployments
Audit application code for paths where untrusted input flows into metric names or values and refactor to use fixed, enumerated metric labels
Validate observability data integrity for the window preceding the patch, since injected metrics may have already polluted historical dashboards

Patch Information

Version 0.04 of the module modifies the _make method to reject metric names containing characters below ASCII 32 (including newline), colons, or pipes. The fix is documented in the MetaCPAN Change Log. Related advisories include CVE-2026-46719, CVE-2026-46720, and CVE-2026-46739, which cover related metric injection issues across the Perl metrics ecosystem.

Workarounds

Sanitize all strings passed as metric names or values by stripping or rejecting \n, \r, :, and | characters before invoking the adapter
Restrict metric names to a known allowlist of enumerated identifiers rather than dynamic, request-derived values
Place the statsd collector behind a parser or proxy that enforces strict line and field validation on inbound packets

bash

# Upgrade the affected module via cpanm
cpanm Metrics::Any::Adapter::Statsd@0.04

# Verify installed version
perl -MMetrics::Any::Adapter::Statsd -e 'print $Metrics::Any::Adapter::Statsd::VERSION, "\n"'