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

CVE-2026-42154 is fixed in 5 products on 1 platform, first by DEBIAN-CVE-2026-42154, released May 4, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-42154
- Priority: High
- CVSS: 8.2 (Moderate)
- EPSS: 0.0081
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 4, 2026
- Weakness: Uncontrolled Resource Consumption
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42154

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | amazon-cloudwatch-agent amzn 2023 | 1.300066.2-2.amzn2023 | [ALAS2023-2026-1747](https://patchblox.com/security/data/fix/linux/alas2023-2026-1747.md) | May 25, 2026 |
| Linux | flightctl RHEL 10 | 1.1.3-1.el10em | [RHSA-2026:41019](https://patchblox.com/security/data/fix/linux/rhsa-2026-41019.md) | May 22, 2026 |
| Linux | govulncheck-vulndb opensuse-leap 16.0 | 0.0.20260723T184607-160000.1.1 | [OPENSUSE-SU-2026:21483-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21483-1.md) | Jul 30, 2026 |
| Linux | opentelemetry-collector RHEL 10 | 0.152.1-1.el10_0 | [RHSA-2026:53413](https://patchblox.com/security/data/fix/linux/rhsa-2026-53413.md) | Jul 2, 2026 |
| Linux | opentelemetry-collector RHEL 9 | 0:0.152.1-1.el9_8 | [RHSA-2026:34359](https://patchblox.com/security/data/fix/linux/rhsa-2026-34359.md) | Jul 2, 2026 |
| Linux | opentelemetry-collector almalinux 10 | 0.152.1-1.el10_2 | [ALSA-2026:34357](https://patchblox.com/security/data/fix/linux/alsa-2026-34357.md) | Jul 1, 2026 |
| Linux | opentelemetry-collector almalinux 9 | 0.152.1-1.el9_8 | [ALSA-2026:34359](https://patchblox.com/security/data/fix/linux/alsa-2026-34359.md) | Jul 1, 2026 |
| Linux | opentelemetry-collector rocky 10 | 0:0.152.1-1.el10_2 | [RLSA-2026:34357](https://patchblox.com/security/data/fix/linux/rlsa-2026-34357.md) | Jul 7, 2026 |
| Linux | opentelemetry-collector rocky 9 | 0:0.152.1-1.el9_8 | [RLSA-2026:34359](https://patchblox.com/security/data/fix/linux/rlsa-2026-34359.md) | Jul 5, 2026 |
| Linux | prometheus Debian 14 | 3.5.3+ds1-1 | [DEBIAN-CVE-2026-42154](https://patchblox.com/security/data/fix/linux/debian-cve-2026-42154.md) | May 4, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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