CVE-2026-42154

Summary

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.

Affected Software

Weaknesses

• CWE-400: CWE-400: Uncontrolled Resource Consumption
• CWE-789: CWE-789: Memory Allocation with Excessive Size Value

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: yes
  • Technical Impact: partial

github.com/prometheus/prometheus: Prometheus: Denial of Service via uncontrolled memory allocation in remote read endpoint

Additional References

• https://access.redhat.com/security/cve/CVE-2026-42154
• https://bugzilla.redhat.com/show_bug.cgi?id=2466505
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42154.json
• https://access.redhat.com/errata/RHSA-2026:34357
• https://access.redhat.com/errata/RHSA-2026:34359
• https://access.redhat.com/errata/RHSA-2026:34364
• https://access.redhat.com/errata/RHSA-2026:30651
• https://access.redhat.com/errata/RHSA-2026:25039
• https://access.redhat.com/errata/RHSA-2026:29770
• https://access.redhat.com/errata/RHSA-2026:25245

References

• https://github.com/prometheus/prometheus/security/advisories/GHSA-8rm2-7qqf-34qm
• https://github.com/prometheus/prometheus/pull/18584
• https://github.com/prometheus/prometheus/pull/18585
• https://github.com/prometheus/prometheus/releases/tag/v3.11.3
• https://github.com/prometheus/prometheus/releases/tag/v3.5.3

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