CVE-2025-43915Network attack vector

Proxy memory exhaustion via unbounded hostname metrics

Published May 5, 2025 · Updated May 19, 2025

Resource exhaustion in Linkerd proxy metrics allows remote attackers to consume proxy memory through crafted HTTP requests. The proxy records every unique inbound authority or outbound hostname as a Prometheus metric label without bounding label cardinality. Exposure requires HTTP traffic with unconstrained hostnames; sustained requests can exhaust proxy memory, overwhelm metrics ingestion, or increase ingestion costs.

CVSS severity6.5
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Linkerd proxy metrics allows remote attackers to consume proxy memory through crafted HTTP requests. The proxy records every unique inbound authority or outbound hostname as a Prometheus metric label without bounding label cardinality. Exposure requires HTTP traffic with unconstrained hostnames; sustained requests can exhaust proxy memory, overwhelm metrics ingestion, or increase ingestion costs.

The record

CVE
CVE-2025-43915
Published
May 5, 2025
Updated
May 19, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 5, 2025CVE publishedPublication date reported by the CVE source.
  2. May 19, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
5.2BuoyantCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L/E:P/RL:O/RC:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
CWE-770Allocation of Resources Without Limits or Throttling
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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