CVE intelligence

CVE-2026-42154

Vulnerability intelligence

Published May 4, 2026Sources checked Nov 12, 2026

7.5HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-42154 and is rated High severity with a CVSS score of 7.5. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Sep 25, 2026

CBL-Mariner Releases

Vendor-listed releases

1.31.0-20

CISA KEVNot listedBased on the latest collected catalog

EPSS0.8%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-42154?

Prometheus is an open-source monitoring system and time series database. Prior to versions 3.5.3 and 3.11.3, the remote read endpoint (/api/v1/read) does not validate the declared decoded length in a snappy-compressed request body before allocating memory.

An unauthenticated attacker can send a small payload that causes a huge heap allocation per request. Under concurrent load this can exhaust available memory and crash the Prometheus process.

This issue has been patched in versions 3.5.3 and 3.11.3.

Source: NVD