CVE-2026-42154
Analyzed Analyzed - Analysis Complete
Memory Exhaustion in Prometheus via Snappy Compression

Publication date: 2026-05-04

Last updated on: 2026-05-11

Assigner: GitHub, Inc.

Description
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.
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Meta Information
Published
2026-05-04
Last Modified
2026-05-11
Generated
2026-06-16
AI Q&A
2026-05-05
EPSS Evaluated
2026-06-15
NVD
CVE-2026-42154
EUVD
EUVD-2026-27091
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
prometheus prometheus to 3.5.3 (exc)
prometheus prometheus From 3.6.0 (inc) to 3.11.3 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-789 The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.
CWE-400 The product does not properly control the allocation and maintenance of a limited resource.
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Executive Summary

This vulnerability exists in Prometheus versions prior to 3.5.3 and 3.11.3, specifically in the remote read endpoint (/api/v1/read). The issue is that the system does not validate the declared decoded length in a snappy-compressed request body before allocating memory. This means an attacker can send a small payload that tricks the system into allocating a very large amount of memory.

Because the memory allocation is based on unvalidated input, an unauthenticated attacker can cause excessive memory usage, potentially leading to the exhaustion of available memory and crashing the Prometheus process.

Impact Analysis

The primary impact of this vulnerability is a denial of service (DoS) condition. An attacker can cause Prometheus to consume excessive memory by sending specially crafted requests, which can lead to the Prometheus process crashing.

This can disrupt monitoring and alerting services that rely on Prometheus, potentially causing loss of visibility into system health and delays in detecting other issues.

Mitigation Strategies

To mitigate this vulnerability, you should upgrade Prometheus to version 3.5.3 or 3.11.3 or later, as these versions contain the patch that fixes the issue.

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