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CVE-2026-42154

HIGHCVSS 7.5/10EPSS 0.81%

Last modified

CVE-2026-42154 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.81% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability
0.81%

54.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
PrometheusPrometheus< 3.5.3
PrometheusPrometheus>= 3.6.0, < 3.11.3

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

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.
How severe is CVE-2026-42154?
CVE-2026-42154 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.81% probability of exploitation in the next 30 days.
How do I fix CVE-2026-42154?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST