What’s Vulnerable › Vulnerabilities

CVE-2026-42154: Prometheus: remote read endpoint allows denial of service via crafted snappy payload

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-04 · updated 2026-09-10
• Weakness: CWE-400

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.

Affected products

• prometheus: before 3.5.3; from 3.6.0 before 3.11.3 — fixed in 3.11.3, 3.5.3

How to fix

Upgrade to a fixed version: prometheus 3.11.3, 3.5.3. Check the vendor advisory for mitigations.

References

• 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
• https://github.com/prometheus/prometheus/security/advisories/GHSA-8rm2-7qqf-34qm
• https://access.redhat.com/errata/RHSA-2026:25039
• https://access.redhat.com/errata/RHSA-2026:25245
• https://access.redhat.com/errata/RHSA-2026:29770
• https://access.redhat.com/errata/RHSA-2026:30651
• https://access.redhat.com/errata/RHSA-2026:34357
• https://access.redhat.com/errata/RHSA-2026:34359
• https://access.redhat.com/errata/RHSA-2026:34364

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